WASHINGTON - THE US Justice Department said on Wednesday it had launched a criminal investigation into the CIA's destruction of videotapes showing the harsh interrogation of terrorism suspects.

'There is a basis for initiating a criminal investigation of this matter, and I have taken steps to begin that investigation,' said Attorney General Michael Mukasey.

The Central Intelligence Agency last month disclosed that in 2005 it destroyed hundreds of hours of tapes from the interrogations of two al Qaeda suspects, prompting an outcry from Democrats, human rights activists and some legal experts.

President George W. Bush has said the United States does not torture but has declined to be specific about interrogation methods.

The Justice Department and the CIA's inspector general last month launched an initial inquiry into the destruction of the tapes.

The CIA says it acted lawfully in destroying the tapes, but critics say the agency flouted court orders and investigators' requests that it hand over evidence in various terrorism cases.

A Justice Department official declined to specify what laws may have been violated.

'Those tapes may have been evidence of a crime, and their destruction may have been a crime in itself,' said Senator Edward Kennedy, a Massachusetts Democrat and member of the Judiciary Committee.

Democratic Senator Patrick Leahy of Vermont, the Judiciary Committee's chairman, said the investigation's launch 'shows that many of us were right to be concerned with possible obstruction of justice and obstruction of Congress.'

Congressional intelligence committees, which are seeking testimony from senior CIA officials believed involved in the destruction, signalled they would continue their investigations despite the federal probe.

The Justice Department had initially balked at the congressional investigations, saying they could undermine its own efforts, and lawmakers accused the Bush administration of trying to cover up the controversy.

'Our negotiations with the CIA and (Justice Department) over the scope of our investigation are ongoing. I fully expect their continued cooperation, including relevant testimony and documents,' said Senate Intelligence Committee Chairman John Rockefeller, a West Virginia Democrat.

The CIA said it would 'cooperate fully with this (federal) investigation, as it has with others into this matter.'

The agency's inspector general, John Helgerson, said he would step aside from the Justice Department's investigation despite taking part in the initial probe.

Inspector Helgerson said the inspector general's office had reviewed the tapes 'some years ago' as part of a study of agency interrogations and that he had helped prepare a report on the issue, so it would be inappropriate to be involved in the probe.

Mr Mukasey said he had directed the FBI to conduct the investigation under the supervision of a federal prosecutor from Connecticut, John Durham. -- REUTERS