The story...

bin Ladin has denied committing the 9/11 attacks. Any subsequent apparent admissions come from forged video or audio tapes.

Our take...

Denials were certainly reported almost immediately after the attacks. Pravda carried this brief report, for instance:

Notorious international terrorist Osama Bin Laden denies his involvement in the US terrorist acts. The Pakistani Khabrein daily with reference to some Taliban sources quotes him as saying that the terrorist act was committed by some American terrorist group and that he had nothing to do with it.
Source

That sounds emphatic, if a little remote: Pravda reporting what Khabrein say a Taliban source has told them that bin Ladin said. And the Taliban are an obvious weak link in that chain. They would not have wanted to be bombed into oblivion by the US, so had a strong incentive either to ask bin Ladin to deny responsibility, or perhaps issue the denial themselves.

There are other denials, too, however. The most detailed and commonly quoted comes from an interview by a Pakistani newspaper, the Daily Ummat.

The paper quoted bin Laden as saying: "Neither I nor my organisation Al-Qaida is involved in the attacks and the US has traced the attackers within America.

"The attackers could be anybody, people who are part of the American system yet rebel against it, or some group that wants to make this century a century of confrontation between Islam and Christianity," he said.

Referring to evidence obtained by American intelligence, bin laden said: "Ask this question to these intelligence agencies that get billions of dollars every year."

Ummat quotes bin Laden as saying: "We are against the American system but not the American people. Islam does not allow killing of innocent people, men, women and children even in the event of war."
http://web.archive.org/web/20010929010503/http://www.ananova.com/news/story/sm_410936.html

This sounds unequivocal, but can we be sure of its authenticity? Perhap not:

The newspaper says it submitted questions for bin Laden to Taliban officials and received written replies.
http://web.archive.org/web/20010929010503/http://www.ananova.com/news/story/sm_410936.html

Certainly the Ummat statement that “Islam does not allow the killing of innocent people, men, women and children” doesn’t sit well with earlier bin Ladin interviews. Here’s what he told John Miller in 1998 (our emphasis):

PBS: Mr. bin Laden, you have issued a fatwah calling on Muslims to kill Americans where they can, when they can. Is that directed at all Americans, just the American military, just the Americans in Saudi Arabia?

bin Ladin: Allah has ordered us to glorify the truth and to defend Muslim land, especially the Arab peninsula ... against the unbelievers. After World War II, the Americans grew more unfair and more oppressive towards people in general and Muslims in particular. ... The Americans started it and retaliation and punishment should be carried out following the principle of reciprocity, especially when women and children are involved. Through history, American has not been known to differentiate between the military and the civilians or between men and women or adults and children. Those who threw atomic bombs and used the weapons of mass destruction against Nagasaki and Hiroshima were the Americans. Can the bombs differentiate between military and women and infants and children? America has no religion that can deter her from exterminating whole peoples. Your position against Muslims in Palestine is despicable and disgraceful. America has no shame. ... We believe that the worst thieves in the world today and the worst terrorists are the Americans. Nothing could stop you except perhaps retaliation in kind. We do not have to differentiate between military or civilian. As far as we are concerned, they are all targets, and this is what the fatwah says ... . The fatwah is general (comprehensive) and it includes all those who participate in, or help the Jewish occupiers in killing Muslims.
http://www.pbs.org/wgbh/pages/frontline/shows/binladen/who/interview.html

No great sympathy for civilians here, so perhaps there’s another reason for bin Ladin’s reticence in accepting responsibility for 9/11. For example, if bin Ladin admitted the attacks immediately then he instantly gave America a pretext for war. By denying them he ensures a degree of uncertainty, meaning the US is more likely to be criticised if they begin any attacks.

There may arguably have been similar reasoning behind a further denial to CNN, where bin Ladin specifically defended “the current leader” of Afghanistan:

In a statement issued to the Arabic satellite channel Al Jazeera, based in Qatar, bin Laden said, "The U.S. government has consistently blamed me for being behind every occasion its enemies attack it.

"I would like to assure the world that I did not plan the recent attacks, which seems to have been planned by people for personal reasons," bin Laden's statement said.

"I have been living in the Islamic emirate of Afghanistan and following its leaders' rules. The current leader does not allow me to exercise such operations," bin Laden said.
http://archives.cnn.com/2001/US/09/16/inv.binladen.denial/

Hamid Mir, bin Laden’s Pakistani biographer, revealed a very different story in account given to Peter Bergen:

I was not ready to say that bin Laden is involved in the [9/11] attacks. You see, I was questioning the assumption that he is involved. When I visited Afghanistan, I spent some days there, I was totally changed because I saw the pictures of Atta [the lead hijacker] hanging in the [al Qaeda] hideouts. Privately they admitted everything. They said, they [who attacked on 9/11] are our brothers, but they said that “When the Americans kill Muslims in Sudan, they don’t admit that we are responsible for the attacks. When the Indians kill Kashmiris, they don’t admit that we have killed them. So now this is our turn. We have killed them and we are not going to admit that.

My tape recorder was on and one very important al Qaeda leader he turned off my tape recorder and said, “Yes, I did it. Okay. Now play your tape recorder.” I played the tape recorder and he said “No, I’m not responsible”.

Hamid Mir interview with Peter Bergen, Islamabad, May 11 2002 and March 2005
Chapter 10
The Fall of the Taliban and the Flight to Tora Bora
The Osama bin Laden I Know
Peter L Bergen

This approach didn’t last for long, though. Soon after the initial denial, both bin Ladin and other Al Qaeda members have made many admissions that variously accept that Muslims were involved, that they were those named by the US, or that Al Qaeda were directly responsible.

7th October 2001: bin Ladin

In this statement he appears to be saying that the attacks were committed by Muslims, and threatens the possibility of more

When Almighty God rendered successful a convoy of Muslims, the vanguards of Islam, He allowed them to destroy the United States...

I swear by Almighty God who raised the heavens without pillars that neither the United States nor he who lives in the United States will enjoy security before we can see it as a reality in Palestine and before all the infidel armies leave the land of Mohammed, may God's peace and blessing be upon him.
http://news.bbc.co.uk/1/low/world/south_asia/1585636.stm

October 9th, 2001: Suleiman Abu-Ghaith

Just in case that’s not enough, another Al Qaeda spokesman makes the threat explicit:

"He issued a chilling warning to the U.S., saying there would be no peace until it stops supporting Israel and ends blockades against Iraq.

"The youths who did what they did and destroyed America, they have done a good deed," he said. "The storm of airplanes will not stop. There are thousands of young people who look forward to death like the Americans look forward to living."
www.cbc.ca/story/world/national/2001/10/09/alqaeda_warn011009.html

14th October: Suleiman Abu Ghaith

And the same message is repeated a few days later. Why would someone who knew nothing of, and disagreed with the attacks threaten more?

Finally, I address the US secretary of state, who cast doubt about my previous statement and downplayed what we said that there are thousands of Muslim youths who are eager to die and that the aircraft storm will not stop, God willing.

"Powell, and others in the US administration, know that if al-Qaeda organisation promises or threatens, it fulfils its promise or threat, God willing.

"Therefore, we tell him tomorrow is not far for he who waits for it. What will happen is what you are going to see and not what you hear.

"And the storms will not calm, especially the aircraft storm...

We also say and advise the Muslims in the United States and Britain, the children, and those who reject the unjust US policy not to travel by plane.

We also advise them not to live in high-rise buildings and towers...
http://news.bbc.co.uk/1/low/world/middle_east/1598146.stm

27th December 2001, bin Ladin:

"Those who carried out the act (September 11) were not 19 Arab countries... they were 19 secondary school students..." He then went on to say how they should all become martyrs, ie: "Another, Muhammed Atta came from Egypt. We beseech God to accept them all as martyrs".
www.fas.org/irp/world/para/ladin_122701.pdf

February 2002, bin Ladin:

Now he appears to be accepting that the attacks were carried out by the Muslims named by America, but claims he did no more than "incite" them:

"What many leaders have said so far is that America has an indication only, and not a tangible proof. They describe those brave guys who took the battle to the heart of America and destroyed its most famous economic and military landmarks.

They did this, as we understand it, and this is something we have agitated for before, as a matter of self-defense, in defense of our brothers and sons in Palestine, and to liberate our sacred religious sites/things. If inciting people to do that is terrorism, and if killing those who kill our sons is terrorism, then let history be witness that we are terrorists".
http://archives.cnn.com/2002/WORLD/asiapcf/south/02/05/binladen.transcript/indexold.html

April 4th, 2002: al Qaeda statement

The first charge of the heroes of the New York and Washington attacks was obedience to all of their orders, an obedience that was established before their departure to the enemy's land, beginning with the hero Ahmad al-Ghamdi, may Allah almighty have mercy on him...

We have put forth this directive in order to deliver a new blow to America and to expose to the world the fallacy of the American propaganda which claims it has irrefutable evidence regarding the warriors (mujahideen) who carried out the operation. It claims it has twenty-four thousand threads leading to knowledge of the agents of the operation. But what appears to it as evidence is weaker than a spider's web, and the American case cannot rely upon it to indict the suspects, let alone convince the world with it. In this directive we say to America that hiding all trace of the agents of the operation was not something we considered. Rather, some of the heroes were intent on leaving Islamic fingerprints on the operation. This is a new blow received by the American security agency that has looked here and there in confusion unlike anything ever seen before. On account of the hunt for a trace of the heroes who entered their country, noses have sniffed with honor and pride.

[there then follows a lengthy justification explaining why they claim the attacks were permissible under Islam]

These comments about the permissibility of the martyrdom operations in the attack of New York and Washington are taken from the book The Truth about the New Crusader War. Whoever wants further evidence and a detailed discussion of the matter should consult the entire book.
http://www.mepc.org/journal_vol10/alqaeda.html

Why are al Qaeda writing about and naming a “hero” of 9/11 if they don’t know anything about it? Doesn’t the statement “hiding all trace of the agents of the operation was not something we considered” indicate their involvement? Why are they bothering to justify the attacks (and write a book about them) if they had nothing to do with it?

No, this is clear acceptance of al Qaeda involvement. Read a detailed analysis of the statement here.

April 2002, Ahmed al-Haznawi:

"For the first time, one of the 19 suicide hijackers involved in the September 11 attacks has been shown explaining his motives, with the broadcast yesterday by an Arab television network of a videotape made last year by a man identified as a Saudi conspirator.
The Qatar-based al-Jazeera station named the man as Ahmed al-Haznawi - a hijacker on United Airlines flight 93 which crashed in Pennsylvania on September 11. He is shown angrily reciting a prepared statement, which al-Jazeera described as a last will and testament".
www.guardian.co.uk/september11/story/0,11209,685127,00.html

September 10th, 2002: bin Ladin and others

"Two days before the anniversary of the September attacks and at a time the U.S. is using its war on terror to launch an attack against Iraq, Qatar’s Al-Jazeera satellite channel on Monday, September 9, aired video-clips in which it says Osama bin Ladin claimed responsibility for the 9/11 attacks on the United States"...

Apart from Atta, bin Ladin named Lebanese Ziyad al-Jarrah, Marwan al-Shehhi from the United Arab Emirates, “who destroyed the second tower” of the World Trade Center, and Hani Hanjour (from the Saudi city of Taef) “who destroyed the Pentagon.”

Al-Jazeera showed photographs of Hamza al-Ghamdi (alias Julailib al-Ghamdi), Saeed al-Ghamdi (alias Mutaz al-Ghamdi), Wael al-Shehri (alias Abu Suleiman) and Ahmad Naami (Abu Hisham), whose names, like those cited by bin Ladin, figure on the U.S. Federal Bureau of Investigation (FBI) list of hijackers.

Al-Jazeera also aired footage of one of the hijackers saying in his “will” that he was trained by Laden.

“May God reward all those who trained me and made possible this glorious act, notably the fighter and mujahid (Islamic warrior) Osama bin Ladin, God protect him,” said Saudi kamikaze Abdul Aziz al-Omari.

Al-Omari, who according to the FBI was one of five hijackers who slammed an American Airlines Boeing 767 into the north tower of the World Trade Center, was shown wearing a grey robe with his shoulder-length hair turbaned in a keffiyeh (chequered headdress).

The September 11 attacks were “a message to all infidels and to America to leave the Arabian peninsula and stop supporting the cowardly Jews in Palestine,” he said.

“Let it be known that we can bring you and other enemies down,” Al-Omari said, addressing the United States.
http://www.islam-online.net/English/News/2002-09/10/article02.shtml

September 2002: Ayman Al Zawahiri

it is imperative that we acknowledge the victory achieved by the Muslims against the Crusader forces, in New York and Washington... This small group, in numbers and equipment, were able to inflict immense slaughter on the greatest idol worshipped today, despite its power and arrogance...
http://www.islamistwatch.org/texts/interviews/zawahiri01.html

October 2002: Ramzi Binalshibh and Khalid Shaikh Mohammed

In an interview by Al Jazeera reporter Yosri Fouda, Ramzi Binalshibh and Khalid Shaikh Mohammed admit responsibility for 9/11, and describe their planning. These interviews were audiotaped, and segments broadcast on Al Jazeera.

“Immediately, Khalid introduces himself as head of the military committee of Al Qaeda,” says Fouda. “That committee actually was the arm of Al Qaeda, which decided, first of all, according to Khalid, to strike America inside America and to eventually choose the targets, which were actually hit on Sept. 11.”
http://www.cbsnews.com/stories/2002/10/08/60II/main524794.shtml

In the second part of a documentary aired by the Arabic television news network Al-Jazeera, two al Qaeda terrorists wanted by the United States give an account of their planning of the September 11 attacks and describe the actions of some of the main hijackers in their final days...

About three weeks before September 11, targets were assigned to four teams, with three of them bearing a code name: The U.S. Capitol was called "The Faculty of Law;" the Pentagon became "The Faculty of Fine Arts;" and the North Tower of the World Trade Center was code-named by Atta as "The Faculty of Town Planning."

One of the terrorists, Abu Abdul Rahman, pretended to send a love message via an Internet chat room to his German girlfriend, who was actually Binalshibh. It contained more code for the attacks:

"The first semester commences in three weeks. Two high schools and two universities. ... This summer will surely be hot ...19 [the eventual number of hijackers] certificates for private education and four exams. Regards to the professor. Goodbye."

Soon after, Fouda says, the hijackers began "moving fast," picking the flights to be hijacked, choosing ones involving large planes with "maximum volume of fuel and best punctuality."

Seats in business class were chosen for some to allow for "mobility and maneuverability," according to Binalshibh.
http://archives.cnn.com/2002/WORLD/meast/09/12/alqaeda.911.claim/indexold.html

March 2003: bin Ladin

...because of the way they oppress us in the Muslim world, especially in Palestine and Iraq, and because of their occupation of the Land of the Two Holy Places... the Mujahideen... decided to act in secret and to move the battle right into his [the U.S. president's] country and his own territory.

They carried out the raid by means of enemy planes in a courageous and splendid operation the like of which mankind had never before witnessed. They smashed the American idols and damaged its very heart, the Pentagon. They struck the very heart of the American economy, rubbed America's nose in the dirt and dragged its pride through the mud. The towers of New York collapsed, and their collapse precipitated an even greater debacle: the collapse of the myth of America the great power and the collapse of the myth of democracy; people began to understand that American values could sink no lower. The myth of the land of freedom was destroyed, the myth of American National security was smashed and the myth of the CIA collapsed, all praise and thanks to Allah.
http://memri.org/bin/opener.cgi?Page=archives&ID=SP47603
http://www.robert-fisk.com/englishtext_usama_tape_14Feb2003.htm

May 2003: Ayman Al Zawahiri

Learn from your 19 brothers who attacked America in its planes in New York and Washington and caused it a tribulation that it never witnessed before and is still suffering from its injuries until today.
http://news.bbc.co.uk/2/hi/middle_east/3047903.stm

September 21, 2003: Abu Muhammad al-Ablaj

Abu Muhammad al-Ablaj, "the man in charge of training in al-Qa'ida", describes bin Ladin as "the one who destroyed its economic pride, sullied its military dignity and wrecked the impregnable Pentagon fortress". Also says of "The September Team": the soldiers of The Most Gracious who implemented are gone to their Lord in that regiment. The brains that plan still remain".
http://www.why-war.com/news/2003/09/21/alqaidas.html

August 2004: Abu-Jandal

The former personal bodyguard of bin Ladin and leading Al Quaeda member in Yemen says "among the elements that carried out the September incidents I knew Muhammed Atta..."
http://www.why-war.com/news/2004/08/03/binladin.html

October 30th 2004: bin Ladin

I say to you, Allah knows that it had never occurred to us to strike the towers. But after it became unbearable and we witnessed the oppression and tyranny of the American/Israeli coalition against our people in Palestine and Lebanon, it came to my mind..."

"And as I looked at those demolished towers in Lebanon, it entered my mind that we should punish the oppressor in kind and that we should destroy towers in America in order that they taste some of what we tasted and so that they be deterred from killing our women and children"
http://www.worldpress.org/Americas/1964.cfm

September 12th 2005:
American Al-Qaeda operative Adam Gadahn:

Four years after the blessed raids on New York and Washington, we find the people of the West continuing to speculate about the causes and objectives which lie behind those historic events and subsequent developments. We find them in disagreement over the nature of the people who carry out operations like those on September 11th, March 11th, and July 7th, the nature of their motives, and the nature of the demands they harbor, if any. And most crucially, and as a result of their speculation and disagreement, we find them uncertain about which steps or actions they must take to achieve the restoration of the security they once enjoyed.

Allah is our witness that the numerous audio and videotapes issued by Sheikh Osama bin Ladin, Dr. Ayman al-Zawahiri, and the other leaders of the jihad have... been released to explain and propound the nature and goals of the worldwide jihad against America and the Crusaders and convey our legitimate demands to friend and foe alike...

As Sheikh Osama has told you repeatedly, your security is dependent on our security. You can't have one without the other. If you ensure our security, you will have automatically ensured your own.
http://www.memritv.org/Transcript.asp?P1=850

May 24th 2006: bin Ladin (unconfirmed?):

Zacarias Moussaoui's role in the Sept. 11, 2001, attacks was fiercely debated at his recent death penalty trial, with the al-Qaeda conspirator and prosecutors agreeing that he was to fly a fifth hijacked airplane into the White House and defense lawyers insisting he was lying.

Now, someone who ought to know has weighed in: Osama bin Laden.
 
The fugitive al-Qaeda leader issued a videotape yesterday in which he claims that Moussaoui had "no connection whatsoever with the events of September 11" and that he knows this because "I was responsible for entrusting the 19 brothers, Allah have mercy upon them, with those raids."

Bin Laden also says in the 4-minute, 34-second message that the hundreds of prisoners the U.S. military is holding at Guantanamo Bay, Cuba, "have no connection whatsoever to the events of Sept. 11 and even stranger is that many of them have no connection with al-Qaeda in the first place."

It cannot be determined whether bin Laden is telling the truth, and a U.S. counterterrorism official said the tape is being analyzed. But the official said there is "no reason to doubt that it's real" and that it "was obviously done in recent weeks." The official said analysts believe that as in other recent al-Qaeda releases, bin Laden is trying "to appear relevant and to demonstrate that he's knowledgeable about current events."
http://www.washingtonpost.com/wp-dyn/content/article/2006/05/23/AR2006052301262.html

June 13th 2006: Al Qaeda statement:

DUBAI, United Arab Emirates - A Saudi militant killed in 2004 was due to have been the 20th suicide plane hijacker in the Sept. 11, 2001 attacks, al-Qaida’s media arm said in a statement on the Internet on Tuesday.

“Turki bin Fheid al-Muteiri -- Fawaz al-Nashmi -- may God accept him as a martyr (was) the one chosen by Sheikh Osama bin Laden to be the martyrdom-seeker number 20 in the raid on September 11, 2001,” the statement said.

“The (Sept. 11) operation was brought forward for some circumstances that brother Mohamed Atta explained to the general leadership,” it said, indicating that Muteiri could not join the other hijackers, led by Atta, in time.
http://msnbc.msn.com/id/13288953/

December 2006: al-Zawahiri statement:

Realities of the Conflict Between Islam and Unbelief

Shaykh Ayman al-Zawahiri

December 2006
You must realize that a new period of world history has begun. The period of the offspring of Abd al-Aziz Al-Sa’ud, the grandsons of the Sharif Husayn and Sadat, Mubarak and Arafat has passed, and the period of Khalid Islambouli, Abdullah Azzam, Abu Hafs the Commander, Khattab, Muhammad Atta, Muhammad Siddique Khan, and Shehzad Tanwir (Allah have mercy on them) has begun. And if you are unable to comprehend this transformation, then blame no one but yourselves.
http://www.lauramansfield.com/j/zawahiri_122006.asp