The US Senate Intelligence Committee has voted to declassify its long-awaited report on the CIA's use of brutal interrogation methods that critics say amount to torture.

The committee chair, Democrat Senator Dianne Feinstein, said the vote was 11-3 to declassify what she called the "shocking" results of investigating the CIA practices under President George W Bush.

The vote to lift the blackout on the summary and recommendations of the 6,200-page report follows an unprecedented clash by Ms Feinstein with the CIA.

It would give the world its first official look at its system of interrogation and detentions in the aftermath of the 11 September attacks.

"The report exposes brutality that stands in stark contrast to our values as a nation," Ms Feinstein told reporters after the vote.

"It chronicles a stain on our history that must never be allowed to happen again. This is not what Americans do."

It will still be weeks, if not longer, before any of the document is cleared for release.

Congressional and intelligence sources said the report strongly condemned now-abandoned interrogation techniques such as "waterboarding" or simulated drowning.

They said it concluded that they did not produce significant counter-terrorism breakthroughs.

The report is at the centre of a bitter dispute between Ms Feinstein and the spy agency over whether the CIA secretly monitored the panel's investigation.

Ms Feinstein, normally one of Congress' strongest supporters of the intelligence community, accused the CIA in March of spying on Congress as it conducted the probe and possibly breaking the law.

A top CIA lawyer complained to the Justice Department that Senate investigators accessed privileged agency records without proper authorisation.

Yesterday, Ms Feinstein said the report points to "major problems" with the CIA's management of the interrogation programme, and its interaction with the White House, Congress and other parts of government.

The Senate panel will now ask the White House to declassify the politically sensitive report.

An administration spokeswoman said US President Barack Obama wanted this to happen as expeditiously as possible.

Mr Obama halted the interrogation programme shortly after taking office in 2009.

"The president believes that bringing this programme into the light will help the American people understand what happened in the past and can help guide us as we move forward, so that no administration contemplates such a programme in the future," spokeswoman Caitlin Hayden said in a statement.

CIA Director of Public Affairs Dean Boyd said the agency would act quickly.

He said the agency had learned from the interrogation and detention programme's shortcomings and had taken corrective measures, but indicated it would not sign off on an inaccurate report.

The CIA has taken issue with some of the findings and has said the report contains factual errors.

"We owe it to the men and women directed to carry out this programme to try and ensure that any historical account of it is accurate," Mr Boyd said.

Some committee Republicans voted with the Democrats in favour of declassifying the report.

The investigation began four years ago but was conducted only by Democrats.

Republicans declined to participate because they felt it was too biased.

The three 'no' votes were all from Republicans - Senators Dan Coats of Indiana, Marco Rubio of Florida and James Risch of Idaho.

In a joint statement, Mr Rubio and Mr Risch called the report "one-sided and partisan" and said its release could endanger Americans overseas and risk US relations with other countries.