"We haven't seen anything like this since the 18 1/2-minute gap on the tapes of Richard Nixon," said Sen. Edward Kennedy, D-Mass., in a speech on the Senate floor.
Kennedy and Sen. Richard J. Durbin, D-Ill., said it was possible that people at the agency had engaged in obstruction of justice, The New York Times reported. Both called for Attorney General Michael Mukasey to investigate.
Rep. Jane Harman, D-Calif. and head of the Homeland Security subcommittee on intelligence and terrorism risk assessment, said she warned CIA officials not to destroy any videotapes pertaining to interrogation practices when she was the ranking Democrat on the House Intelligence Committee in early 2003.
"To my knowledge, the Intelligence Committee was never informed that any videotapes had been destroyed," Harman said, the Times reported. "Surely I was not."
The Congresswoman said she received "a highly classified briefing" on CIA interrogation practices in early 2003 from the agency's general counsel, and that she later wrote the lawyer a letter expressing "serious concerns."
"I call for my letter of February 2003, which was never responded to and has been in the CIA's files ever since, to be declassified," she said.
The White House said President Bush did not recall being told about the tapes or their destruction before Thursday, when he was briefed by the CIA director, Reuters reported.
Bush maintains confidence in CIA Director Michael Hayden, White House spokeswoman Dana Perino said. She declined to comment on whether any laws were broken, saying the facts of the situation were still being gathered.
"I asked the president about whether he knew about the tapes and their existence or their destruction, he said he had no recollection of that," Perino said. "He did not remember being made aware of those prior to [Thursday] morning."
The videotapes showed agency operatives in 2002 subjecting terrorism suspects - including Abu Zubaydah, the first detainee in C.I.A. custody - to severe interrogation techniques, according to the Times. The tapes were destroyed in part because officers were concerned that video showing harsh interrogation methods could expose agency officials to legal risks, several officials said.
Hayden told CIA employees that House and Senate intelligence committee leaders were informed about the tapes and the CIA's intention to destroy them in 2003, which some members of Congress disputed, the Associated Press reported. He also said the CIA's internal watchdog watched the tapes and verified that the interrogation practices were legal. The tapes were destroyed in late 2005.
The Center for Constitutional Rights, which coordinates the work of attorneys who represent U.S. prisoners held at Guantanamo Bay Naval Base, said the CIA may have destroyed crucial evidence a court said it was entitled to in 2004.
The group filed a Freedom of Information Act lawsuit in 2004 that has forced the Defense Department and other government agencies to release thousands of documents.
CCR said Friday it is now "deeply concerned" the CIA may have destroyed evidence relating to Majid Khan, a former CIA detainee now held at Guantanamo.
The tapes' revelation may affect ongoing terrorism trials.
Daniel Marcus, an American University law professor who served as general counsel for the Sept. 11 commission and was involved in the discussions about interviews with al-Qaida leaders, said he had heard nothing about any tapes being destroyed, the AP reported.
If tapes were destroyed, he said, "it's a big deal, it's a very big deal," because it could amount to obstruction of justice to withhold evidence being sought in criminal or fact-finding investigations.