The U.S. Senate intelligence committee approved a report on Thursday that the panel's chairwoman said included "startling details" about counter-terrorism practices used by the CIA under former President George W. Bush.
Senator Olympia Snowe of Maine was the sole Republican who supported the move, joining the panel's eight Democrats in a 9-6 vote. Republicans had largely boycotted the three-year investigation, saying it contained inaccuracies and faulting Democrats for calling too few witnesses.
The nearly 6,000-page report is classified and it is not clear whether a version will ever be made public.
But Senator Dianne Feinstein, the California Democrat who chairs the committee, said it raised important issues and should make clear that the country should never use coercive techniques like those it discussed.
"The report uncovers startling details about the CIA detention and interrogation program and raises critical questions about intelligence operations and oversight," she said in a statement.
Reuters reported in April that the three-year investigation was expected to find little evidence that the interrogations produced counter-terrorism breakthroughs. They included the use on a few high-level suspects of a simulated drowning technique known as "waterboarding."
The document includes details of each detainee in CIA custody, the conditions under which they were held, how they were interrogated, the intelligence they provided and the accuracy of CIA descriptions of the program to the White House.
"I believe it to be one of the most significant oversight efforts in the history of the United States Senate, and by far the most important oversight activity ever conducted by this committee," Feinstein said.
With the vote, the Senate intelligence committee also approved the report's 20 findings and conclusions.
Georgia Republican Saxby Chambliss, the committee's vice chairman, did not vote to approve the document.
"I've already said there were lots of inaccuracies," Chambliss told reporters after the vote, and answered "yes," when asked if he still felt that way after seeing the final document.
Chambliss said he did not feel it should be declassified.
Feinstein said she would provide the report to President Barack Obama and officials for review, and the decision on whether to declassify it would be made after receiving their comments.
She told reporters those comments were due back Feb. 15.
IMPASSIONED LETTER FROM MCCAIN
Senator John McCain, an Arizona Republican who was tortured when he was held prisoner during the Vietnam War, sent an impassioned letter to the committee urging that the report be made public.
"It is my hope that we can reach a consensus in this country that we will never again engage in these horrific abuses, and that the mere suggestion of doing so should be ruled out of our political discourse, regardless of which party holds power," he wrote.
Part of the committee's investigation was to evaluate whether the "enhanced interrogation" methods, which also included stress techniques that human rights activists and many U.S. politicians condemn as torture, were effective in producing useful intelligence.
Human rights groups applauded the vote, and said the report should be made public.
"The investigation and report are ... an important precedent for establishing checks and balances between Congress and a CIA that has often flouted both the law and American values," said Christopher Anders, senior legislative counsel at the American Civil Liberties Union, in a statement.
"Only by knowing what happened at the CIA can Congress ensure that it does not happen again," he said.
Republicans had stopped cooperating with the investigation around the time Obama's Justice Department gave a Connecticut-based federal prosecutor, John Durham, a special assignment to investigate whether any U.S. laws were broken by CIA personnel who worked on the interrogation program.
That inquiry was closed earlier this year without criminal charges being filed.
The vote came as a new film, "Zero Dark Thirty," about how the CIA found Osama bin Laden, put interrogation back into the spotlight. The movie includes a scene showing a suspect being waterboarded, reigniting debate over whether the U.S. government engaged in torture.
West Virginia Democratic Senator Jay Rockefeller was asked after the vote whether harsh interrogation techniques helped to find bin Laden. He gave credit to the Navy special forces who killed the man behind the Sept. 11, 2001, attacks.
"I think the SEALs had more to do with that," Rockefeller told reporters.
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