LONDON - British spy agencies are under growing pressure to reveal how closely they worked with their US counterparts following 9/11 after a damning US Senate report exposed how the CIA tortured terror suspects.

The revelations, published on Tuesday, have dragged Britain’s domestic spy agency MI5 and its foreign intelligence counterpart MI6 back into the spotlight and led to calls for a full judge-led inquiry.

Britain was Washington’s closest partner in the “War on Terror” and questions about British involvement in abuses have rankled for years, along with doubts about the close alignment with US foreign policy.

Tom Davies from Amnesty International said Britain seemed “afraid to turn over the rock for fear of what it will find underneath.”

The British-based rights group has launched an online petition calling for the opening of a criminal investigation that had received nearly 14,000 signatures by Friday. Britain’s press has also been unusually united in demanding that the public know what the security services did on their behalf.

“America now knows the truth about what it did. We in Britain do not,” Jenni Russell wrote in a Times comment piece demanding the publication of details about British involvement that were “removed” from the US report.

Downing Street on Thursday admitted that the Senate had given British agencies “limited sight of some sections” and that they had “highlighted a small number of issues in the proposed text where changes would be necessary to protect UK national security”. But it said that “there was no question of the UK seeking redactions over any allegations of UK involvement in activity that would be unlawful in the UK.”

Prime Minister David Cameron admitted in 2010 that “there are questions over the degree to which British officers were working with foreign security services who were treating detainees in ways they should not have done.”

He then asked retired judge Peter Gibson to lead an independent investigation, which produced a preliminary report that raised 27 serious queries about the behaviour of British security officers.

Specifically, Gibson said he wished to investigate “whether in some cases, UK officers may have turned a blind eye to the use of specific, inappropriate techniques or threats used by others”.

Parliament’s intelligence and security committee (ISC) then took over the reins and is due to publish its conclusions at the end of 2015, but that is unlikely to dampen calls for further action.

“Once the police investigations are done, once this report from the Intelligence and Security Committee is done, we should keep an open mind ... about moving to a full judicial inquiry if there are any outstanding questions,” Deputy Prime Minister Nick Clegg, leader of the Liberal Democrats, said Thursday. “I, like everybody else, want the truth out there.”

British intelligence services are particularly concerned by the case of the Ethiopian-born Binyam Mohamed, who was detained in Guantanamo for more than four years before being transferred to Britain in February 2009.

Mohamed claims that a member of MI5 provided questions to be asked during an interrogation, which involved torture, at a secret site in Morocco.

London is also accused of complicity in the kidnapping of Abdelhakim Belhaj, a former jihadist who became military commander of Tripoli after the fall of Moamer Kadhafi in 2011, and his wife.

They claim that British authorities helped the CIA to capture and deliver them to Tripoli, where they were tortured by Kadhafi’s forces.

Meanwhile, the CIA has declassified a letter that suggests US intelligence had grave doubts about part of the case made by former president George W. Bush’s White House to justify the war in Iraq.

In the run-up to the March 2003 invasion, US officials including then vice president Dick Cheney alleged that 9/11 hijacker Mohammed Atta had met an Iraqi spy in Prague before the attacks.

The alleged meeting was cited as evidence of a possible link between Iraqi dictator Saddam Hussein and the September 11, 2001 attacks on New York and Washington.

But, in a letter sent to US Senator Carl Levin in March this year and just now declassified, CIA Director John Brennan said field agents had “expressed significant concern” over the report.

The letter said US agents had not established Atta was in Prague - evidence suggest that he was not - at the time he is supposed to have met Iraqi agent Ahmad Khalil Ibrahim Samir al-Ani.

The letter was first reported by McClatchy newspapers.

Levin said on Thursday he had asked the CIA to declassify the document to show how the former Bush administration “misled” the country before the invasion of Iraq.

In a Senate speech, Levin said the “alleged meeting was a centerpiece of the administration’s campaign to create an impression in the public mind that Saddam was in league with the Al-Qaeda terrorists who attacked us on 9/11.”

“On multiple occasions, including national television appearances, Vice President Dick Cheney cited reports of the meeting, at one point calling it ‘pretty well confirmed,’” Levin said.

Levin said he raised the issue to give “the American people a full account of the march to war as new information becomes available.”

Levin added that the revelation “is about warning future leaders of this nation that they must not commit our sons and daughters to battle on the basis of false statements.”