The American Justice Department has opened a full criminal investigation into the destruction of CIA videotapes believed to show the use of torture during the interrogation of two al-Qaeda suspects in secret overseas prisons.

Michael Mukasey, the United States Attorney General, also announced that the inquiry would be headed by a mob-busting career prosecutor, who will lead a team of FBI agents investigating the decision to destroy the tapes made at CIA 'ghost prisons' overseas five years ago.

The decision to institute a criminal inquiry represents a blow for the CIA, which is also accused of impeding a high-profile investigation into the terror attacks of September 11, 2001.

The White House is at risk of being dragged into the scandal after the revelation that at least four of its staff were approached for advice on what to do with the tapes - although none has admitted to recommending their destruction.

In a statement last night, Mr Mukasey, who replaced Alberto Gonzales in November, said that he had now concluded “that there is a basis for initiating a criminal investigation of this matter" although he said that criminal charges would not necessarily follow.

The criminal probe is being led by John Durham, the first assistant US attorney in Connecticut, whom Mr Mukasey described as“a widely respected and experienced career prosecutor”.

Mr Durham will lead agents from the FBI in determining whether the CIA broke any laws in destroying the tapes. “The CIA will, of course, cooperate fully with this investigation, as it has with the others into this matter,” said Mark Mansfield, a CIA spokesman.

The tapes show the interrogation of two suspects, Abu Zubaydah and Abd al-Rashim, who were held in secret CIA prisons overseas, reportedly in Thailand. According to testimony from a former CIA officer, Zubaydah was subjected to waterboarding, a form of torture that simulates drowning, and "broke" after 35 seconds. Both men are now being held at Guantanamo Bay.

The CIA director, Michae Hayden, said the videos were made in 2002 and destroyed in 2005 to protect the identity of agency operatives. Mr Hayden also said that CIA lawyers had reviewed the material and concluded that the tapes showed “lawful methods of questioning".

Mr Mukasey's explanation for the destruction of the tapes received short shrift from both politicians and human rights campaigners, who accused the agency of trying to cover up torture.

Having queried whether Mr Mukasey was sufficiently independent of the White House to open a criminal inquiry, senior Democrats welcomed his announcement but said they would press ahead with their own hearings in Congress.

“It is essential that the CIA fully cooperate with the criminal probe and with ongoing congressional investigations,” said Harry Reid, the Senate Majority Leader. “If anyone responsible for destroying the tapes did so illegally, they must be held accountable."

Another Democrat, Patrick Leahy, the chairman of the Senate Judiciary Committee, said that Mr Mukasey’s decision “shows that many of us were right to be concerned with possible obstruction of justice and obstruction of Congress".

The White House has insisted that the United States does not torture anyone, but refused to confirm what tactics might have been used to prise information out of detainees.

Meanwhile, lawyers for inmates at the “war on terror” detainment camp at Guantanamo Bay say the CIA has violated a judge’s 2005 order to preserve any possible evidence of detainee mistreatment at the facility in Cuba.

Intensifying the controversy, the CIA yesterday rejected criticism from the co-chairmen of the 9/11 Commission after they accused the agency of obstructed their investigation by withholding sensitive information.

Thomas Kean and Lee Hamilton wrote in The New York Times that the revelations about the videotapes “leads us to conclude that the agency failed to respond to our lawful requests for information about the 9/11 plot".

“Those who knew about those videotapes - and did not tell us about them - obstructed our investigation," they said.

In a statement, the CIA retorted that it was “simply wrong” to state that the agency had obstructed the 9/11 Commission. "And it is disappointing that those who praised CIA publicly for its cooperation with the Commission several years ago now choose to criticise the agency for not being forthcoming."

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