Responding to calls for an accounting of prisoner abuses in the war on terrorism, the head of the U.S. Senate intelligence committee said on Friday her panel would investigate the CIA's treatment of suspects.

The sessions will take place behind closed doors and it remains unclear whether a public version of the findings will be released, a Senate aide said.

"This is not going to be a big dog-and-pony show," the aide said. "This is going to be very much confidential."

Senator Dianne Feinstein, the committee's Democratic chair, confirmed the inquiry after media reports disclosed it and said the panel would have more to say in the near future.

"The Senate Select Committee on Intelligence will conduct a review of the CIA's detention and interrogation practices," she said.

The CIA's program of secret detention of terrorism suspects and harsh, or "enhanced," interrogations has drawn worldwide criticism since its launch after the Sept. 11 attacks in 2001.

President Barack Obama, who took office five weeks ago after eight years of the Bush administration, has banned harsh questioning techniques pending an administration review.

The inquiry is not intended to punish, the Senate aide said.

"The purpose ... is to conduct this review, and have it be a fact-finding, and have it lead to lessons learned," he said.

The CIA has acknowledged that fewer than 100 suspects were held in the secret program, and about one-third of them were subjected to the harsh techniques. It said three suspects experienced "waterboarding," a form of simulated drowning widely considered to be torture.

Former CIA Director Michael Hayden vigorously opposed any new investigation, which he said could undermine employee commitment.

But Obama's CIA chief, Leon Panetta, said in his Senate confirmation hearings earlier this month that the intelligence committee would be an appropriate forum "to learn lessons from what happened." He pledged to cooperate.

He told reporters this week that he would oppose any move to prosecute CIA interrogators who acted based on the legal guidance given by the Bush administration Justice Department.

The review is likely to take six months to year, the aide said. It was unclear whether any witnesses who participate would be required to do so under oath.

The review is separate from a proposal by Senate Judiciary Committee Chairman Patrick Leahy for a South African-style "truth commission" to investigate former President George W. Bush's security policies.

Obama has said he would consider Leahy's proposal but his inclination is to "get it right moving forward" rather than dwelling on the past.