David Cameron is under mounting cross-party pressure to approve a judge-led investigation into whether Britain was involved in the CIA’s torture of suspects during the “war on terror.”

The Prime Minister wants to wait until after an investigation by Parliament’s Intelligence and Security Committee (ISC) before deciding whether another inquiry is needed. But on Sunday, MPs expressed doubts over whether the ISC has the resources to do the job.

Following last week’s report by the Senate Intelligence Committee, many MPs are convinced that British security services witnessed and benefited from the CIA’s torture of terrorist suspects, making them complicit even if they did not take part directly.

It emerged that Jack Straw, who was Foreign Secretary in the Blair government, has been questioned as a witness by police investigating the abduction of two Libyan dissidents in Britain who were handed over to the Gadaffi regime and tortured. The Metropolitan Police is believed to have sent a file to the Crown Prosecution Service.

CIA torture report: Who knew what? Show all 6 1 /6 CIA torture report: Who knew what? CIA torture report: Who knew what? GEORGE W BUSH FORMER US PRESIDENT President Bush has stated in his autobiography that he discussed the programme, including the use of enhanced techniques, with then CIA director George Tenet in 2002, prior to application of the techniques on Abu Zubaydah, and personally approved them. A memoir by the former Acting CIA General Counsel John Rizzo disputes this. AFP/Getty CIA torture report: Who knew what? JOHN BRENNAN FORMER DEPUTY DIRECTOR AND NOW DIRECTOR, CIA Among those who were sent an update on 26 July 2002, in which CIA officers were said to be involved in “sound disorientation techniques,” “sense of time deprivation,” limited light, cold temperatures”, and sleep deprivation. The plan was circulated to senior CIA officers. Getty CIA torture report: Who knew what? CONDOLEEZZA RICE FORMER NATIONAL SECURITY ADVISER On 31 July, 2002, she said that, in balancing the application of the CIA’s interrogation techniques against the possible loss of American lives, she would not object to the CIA’s enhanced interrogation techniques if the Attorney General determined them to be legal. Getty CIA torture report: Who knew what? GEORGE J TENET FORMER DIRECTOR OF CENTRAL INTELLIGENCE, CIA In late January 2003, in response to the death of CIA detainee Gul Rahman and the use of a gun and a drill in the CIA interrogations, DCI Tenet signed the first formal interrogation and confinement guidelines for the programme. Getty CIA torture report: Who knew what? DONALD RUMSFELD FORMER SECRETARY OF DEFENCE Donald Rumsfeld was made aware of the CIA interrogation programme prior to recertification of the covert action for the first time in a 25-minute briefing on 16 September, 2003. It was Condoleezza Rice who ordered his briefing. Getty CIA torture report: Who knew what? COLIN POWELL FORMER SECRETARY OF STATE A CIA email dated 31 July, 2003 states: “The [White House] is extremely concerned [Secretary of State] Powell would blow his stack if he were to be briefed on what’s been going on.” He was formally briefed for the first time on 16 September that year. AFP/Getty

Andrew Tyrie, Tory chairman of an all-party group on rendition, said: “That we are talking about here is kidnap and people being taken to places where they can be maltreated or tortured and I never thought in the 21st century that my country would be facilitating such practices, but they have done; the question is: how much?”

David Davis, the Tory former shadow Home Secretary, told Sky News: “I think this needs to be a judicial inquiry… it needs to be bigger than that [the ISC inquiry]. It needs to be completely independent of the establishment.” What we want out of it is something which says to everybody this will never happen again, indeed, it becomes politically fatal for it to happen on your watch.”

Malcolm Rifkind, right on BBC1’s ‘The Andrew Marr Show’ on Sunday (PA)

Yvette Cooper, the shadow Home Secretary, doubted the ISC had “the capacity and the scope” to carry out an inquiry and it was her “instinct” that a judge-led process would be required to ensure confidence. Norman Baker, the Liberal Democrat former Home Office minister, said: “Based on previous experiences, the ISC has not really delivered the goods. There’s been a suspicion that it has been slightly too close to those who it’s supposed to be overseeing.”

Sir Malcolm Rifkind, the Tory chairman of the ISC, tried to allay fears that his committee would carry out a whitewash, saying it would investigate “without fear or favour”. He added: “If our conclusions are that either serving ministers or former ministers or MI6 or MI5 or anyone else were complicit in torture, we will say so and we will indicate the evidence that has brought us to that conclusion.”

Writing in The Mail on Sunday, Craig Murray, who was sacked as UK ambassador to Uzbekistan in 2004 after alleging that Britain used intelligence obtained by the CIA under torture, said he attended a meeting at the Foreign Office where he was told that “it was not illegal for us to use intelligence from torture as long as we did not carry out the torture ourselves” and claimed this policy came directly from Mr Straw.