"I was responsible for the 9/11 operation from A to Z," Mohammed is quoted as saying in a statement that was read Saturday at a session of his military trial.
According to the transcript, Mohammed claimed responsibility for planning, financing, and training others for bombings ranging from the 1993 attack at the World Trade Center to the attempt by would-be shoe bomber Richard Reid to blow up a trans-Atlantic flight with explosives hidden in his shoes.
In all, Mohammed is quoted as saying that he was responsible for planning 28 individual attacks, including many that were never executed. The comments are in a 26-page transcript released by the Pentagon, which blacked out some of his remarks.
"This so-called confession probably dooms him to a future death sentence," says CBS News legal consultant Andrew Cohen. "There are some close cases down there, some false charges, but this isn't one of them. It's only if he somehow makes it into federal court that his statements could be successfully challenged."
The Pentagon also released transcripts of the hearings of Abu Faraj al-Libi and Ramzi Binalshibh, although Binalshibh refused to attend his hearing.
Binalshibh, a Yemeni, is suspected of helping Mohammed with the Sept. 11, 2001, attack plan and has also been linked by authorities to a foiled plot to crash aircraft into London's Heathrow Airport.
Al-Libi is a Libyan who is suspected of masterminding two bombings, 11 days apart in Pakistan in December 2003, each targeting President Pervez Musharraf for his support of the U.S.-led war on terror.
The hearings, which began last Friday, are being conducted in secret by the military as it tries to determine whether 14 alleged terrorist leaders should be declared "enemy combatants" who can be held indefinitely and prosecuted by military tribunals.
Hearings for six of the 14 have already been held. The military is not allowing reporters to attend the sessions and is limiting the information it provides about them, arguing that it wants to prevent sensitive information from being disclosed.
The 14 were moved in September from a secret CIA prison network to the prison at the U.S. naval base at Guantanamo Bay, where about 385 men are being held on suspicion of links to al Qaeda or the Taliban.
Mohammed's confession was read by a member of the U.S. military who is serving as his personal representative. It also claims he shared responsibility for three other attacks, including assassination attempts against Pope John Paul II and Musharraf.
The transcripts also lay out evidence against Mohammed, saying that a computer seized during his capture included detailed information about the Sept. 11 plot — ranging from names and photos of the hijackers to photos of hijacker Mohammad Atta's pilot's license and even letters from al Qaeda leader Osama bin Laden.
Al-Libi also made a statement through his personal representative largely claiming that the hearing process is unfair and that he will not attend unless it is corrected.
"The detainee is in a lose-lose situation," his statement said.
Binalshibh declined to participate in the process and the hearing was conducted in his absence. Military officials expected some of the 14 suspects not to participate.
Legal experts have criticized the U.S. decision to bar independent observers from the hearings of the detainees who the government describes as "high-value targets." The Associated Press filed a letter of protest, arguing that it would be "an unconstitutional mistake to close the proceedings in their entirety."
Mark Denbeaux, a Seton Hall University law professor who represents two Tunisians held at Guantanamo, said that based on the transcripts, Mohammed might be the only detainee who would qualify as an enemy combatant.
"The government has finally brought someone into Gitmo who apparently admits to being someone who could be called an enemy combatant," Denbeaux, a critic of most of the detentions, said in a telephone interview from London. "None of the others rise to this level. The government has now got one."
The military held 558 combatant status review tribunals between July 2004 and March 2005 and the panels concluded that all but 38 detainees were enemy combatants who should be held. Those 38 were eventually released from Guantanamo.