Senator Kennedy expressed anger about the destruction of the tapes
The CIA says it wiped the tapes to protect the identities of its agents.
But human rights groups accuse it of destroying evidence of practices that may be tantamount to torture.
US President George W Bush has said he has "no recollection" of the existence of the tapes and he was not aware of the plan to destroy them.
Obstructing justice
Senator Dick Durbin, the second most powerful Democrat in the Senate, called on US Attorney General Michael Mukasey to investigate "whether CIA officials who destroyed these videotapes and withheld information about their existence from official proceedings violated the law".
Other Democrats expressed anger about the destruction of the tapes.
'CIA ENHANCED INTERROGATION TECHNIQUES' Water boarding: prisoner bound to a board with feet raised, and cellophane wrapped round his head. Water is poured onto his face and is said to produce a fear of drowning Cold cell: prisoner made to stand naked in a cold, though not freezing, cell and doused with water Standing: Prisoners stand for 40 hours and more, shackled to the floor Belly slap: a hard slap to the stomach with an open hand. This is designed to be painful but not to cause injury Source: Described to ABC News by un-named CIA agents in 2005
CIA boss faces credibility test
"The past six years, the Bush administration has run roughshod over our ideals and the rule of law," said veteran Democratic Senator Edward Kennedy.
"Now, when the new Democratic Congress is demanding answers, the administration is feverishly covering up its tracks," he said.
Carl Levin, Democratic chairman of the Senate Armed Services Committee, cast doubt on the CIA's statement that the tapes were destroyed to protect the identity of its agents.
"You'd have to burn every document at the CIA that has the identity of an agent on it under that theory," he said.
The Senate Intelligence Committee has promised a thorough investigation into the history of the making and wiping of the tapes.
No memory
President Bush continued to have confidence in CIA Director Michael Hayden, White House spokeswoman Dana Perino said.
The president "did not remember" being told of the tapes prior to Thursday, she said.
The CIA revelation has drawn criticism from civil liberties and human rights groups.
This appears to be a part of a long-term pattern of misusing executive authority to insulate individuals from criminal prosecution for torture
ACLU
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Jennifer Daskal, senior counsel with Human Rights Watch, said the wiping of the tapes was "destruction of evidence", and described the reasons given by the CIA as "disingenuous".
The American Civil Liberties Union accused the agency of showing an utter disregard for the law.
"The destruction of these tapes appears to be a part of an extensive, long-term pattern of misusing executive authority to insulate individuals from criminal prosecution for torture and abuse," an ACLU statement said.
Gen Hayden explained why the footage was destroyed in an internal memo sent to CIA employees and obtained by the Associated Press.
He said the CIA had begun taping interrogations as an internal check in 2002 and decided to delete the videos because they no longer had "intelligence value" and posed a security risk.
"Were they ever to leak, they would permit identification of your CIA colleagues who had served in the programme, exposing them and their families to retaliation from al-Qaeda and its sympathisers," he said.
'Torture' questions
The BBC's Jonathan Beale in Washington says the news is likely to trigger more questions about the interrogation techniques used by the CIA and whether they amounted to torture.
Michael Hayden wrote to all CIA employees about the tapes
According to our correspondent, those techniques are alleged to have included water-boarding, a method in which a suspect is made to feel he is drowning.
Human rights groups say that water-boarding - and other techniques allegedly used by the CIA - can be defined as torture under various international treaties to which the US is a signatory.
The Bush administration has always maintained that it does not allow the use of torture.
The tapes are thought to have shown the interrogation in 2002 of a number of terror suspects, including Abu Zubaydah, who had been a chief recruiter for the al-Qaeda network.
CIA Director 
U.S. Congressional Democrats are asking the  to investigate whether the CIA's destruction of videotapes documenting the interrogation of terrorism suspects amounts to obstruction of justice. 

The acknowledgement by Central Intelligence Agency Director  that his agency destroyed the interrogation videotapes in 2005 sparked a firestorm of criticism among Congressional Democrats. They suggested the tapes could have provided key evidence in ongoing trials brought by terrorism suspects who are alleging they were tortured.

Senator , a Massachusetts Democrat, said, "What would cause the CIA to take this action? The answer is obvious - cover up. The agency was desperate to cover up damning evidence of their practices."

Human Rights Watch's Senior Counterterrorism Counsel commented to Google news saying, "The CIA was well aware that its interrogations crossed a line considered by many to be torture. Now some in the CIA may also be guilty of obstruction of justice as well - a serious felony that carries a possible 20 year sentence. There needs to be a serious criminal investigation, and those who have committed crimes should be prosecuted and convicted."

The Democratic chairmen of the  are vowing to investigate, and other Democrats are calling on the Justice Department to do the same.

"You cannot destroy material if there is an ongoing investigation. There is a law against it," said Senator  of Michigan, the chairman of the Senate Armed Services Committee.

At the White House, spokeswoman  said President Bush only learned of the matter two days ago, after he was briefed by CIA Director Hayden.
The United States Capitol building, where Congress meets
"He has no recollection of being made aware of the tapes or their destruction before yesterday," said Perino.

Perino defended the CIA  program as legal and critical to national security. She said President Bush supports General Hayden's explanation that the tapes were destroyed to protect the identities of the interrogators.

But the Senate's number two Democrat, Senator  of Illinois, rejected that argument:

"The defence of the CIA is that they wanted to protect the identity of those CIA employees who were engaged in the interrogation," said Durbin. "Mr. Senate President, that is not a credible defence. We know that it is possible, in fact, easy, to cover the identity and faces of those who were involved in any videotape. Something more was involved here."

The tapes, which documented the use of tough interrogation techniques against key terror suspects in 2002, were destroyed three years later, at a time when there was increasing pressure from defence lawyers to obtain videotapes of detainee interrogations and as Congress had been probing allegations of torture.

The Bush administration has maintained it does not use torture, but refuses to say what techniques are used by intelligence agencies in interrogations of terror suspects.