The US Senate intelligence committee voted on Thursday to release part of a secret report that harshly criticises CIA terror interrogations after September 11 2001.

It voted 11-3 to declassify 500 pages of a 6,300-page review which concluded that waterboarding and other “enhanced interrogation methods” were excessively cruel and ineffective.

The committee and the CIA have been embroiled in a bitter dispute over the study.

Senators have accused the agency of spying on their investigation and deleting files, while the CIA claims Senate staffers illegally accessed information.

The Justice Department is reviewing competing criminal referrals.

Committee chairwoman Dianne Feinstein claimed the report “exposes brutality that stands in sharp contrast to our values as a nation.

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

Leaks of the report said the CIA used secret “black sites” to interrogate prisoners using techniques not previously acknowledged.

These included dunking suspects in icy water and smashing a prisoner’s head against a wall.

Members of the US intelligence community have criticised the investigation for failing to include interviews from top spy agency officials who supervised the brutal interrogations.

“Neither I or anyone else at the agency who had knowledge was interviewed,” claimed Jose Rodriguez, the CIA chief clandestine officer in the mid-2000s, who had operational oversight of the programme.

“They don’t want to hear anyone else’s narrative. It’s an attempt to rewrite history.”

Rodriguez himself is a key figure in the Senate report, not least for his order in 2005 to destroy 92 videos showing waterboarding of terror suspects and other harsh techniques.

Senator Feinstein and others have cited a series of misleading claims by the CIA over the years about the effectiveness of the programme, including in statements made to then president George W Bush and Congress.