A British newspaper splashed a story saying a former MI5 officer wants to “present explosive new evidence” that the Security Service knew inmates at Guantanamo Bay were being tortured.



The unidentified officer wants to reveal his evidence to the parliamentary Intelligence and Security Committee (ISC), it said.



We already know from documentary evidence that officers from MI5 and from MI6, Britain’s Secret Intelligence Service, were aware British residents and citizens, and other detainees and terror suspects, were being tortured in US jails in Afghanistan before being rendered to Guantánamo Bay.



Security and intelligence officers privately discussed how to handle matters they knew would cause problems if disclosed.



MI6 and MI5 sent written guidance to their officers, stating: “Given that they are not within our custody or control, the law does not require you to intervene to prevent this”.



It added: “That said, HMG’s (Her Majesty’s Government) stated commitment to human rights makes it important that the Americans understand that we cannot be party to such ill-treatment nor can we be seen to condone it.”



It continued: “It is important that you do not engage in any activity YOURSELF (my emphasis) that involves inhumane or degrading treatment of prisoners.”



A Foreign Office telegram sent to British embassies in 2002 and signed “Straw” (then foreign secretary) said detainees should be transferred to Guantánamo “as soon as possible”.

They were unlikely to be treated any better there than in the US jails in Afghanistan.



When did MI5 and MI6 chiefs - and the ministers to whom they are accountable - knew about the torture, and what steps did they take to stop it? The questions still await answers.



The Sunday Times, in its splash story this week, said it was understood the former MI5 officer’s evidence would include claims that MI5 officials actually witnessed inmates in Guantanamo being chained, hooded, “waterboarded” and subjected to mental abuse.



Eliza (now Baroness) Manningham-Buller, then head of MI5, has said the government protested to the US over the torture of terror suspects, and that the Americans concealed from Britain the waterboarding of Khalid Sheikh Mohammed, the alleged mastermind of the 9/11 attacks on New York and Washington in 2001.



In her booklet, Securing Freedom, based on her 2011 BBC Reith lectures, she wrote: “Torture is illegal in our national law and in international law. It is wrong and never justified ... Torture should be utterly rejected even when it may offer the prospect of saving lives … I am confident that I know the answer to the question of whether torture has made the world a safer place. It hasn’t.”



Sir John Sawers, who retired last year as head of MI6, described torture as “illegal and abhorrent under any circumstances and we have nothing whatsoever to do with it. If we know or believe action by us will lead to torture taking place, we’re required by UK and international law to avoid that action. And we do, even though that allows the terrorist activity to go ahead.”



He added, however, that if MI6 received credible intelligence that might save lives here or abroad, “we have a professional and moral duty to act on it”.



More than two years ago, a report by Sir Peter Gibson, a former senior judge, concluded that the British government and its intelligence agencies had been involved in rendition operations, in which detainees were kidnapped and flown around the globe, and had interrogated detainees who they knew were being mistreated.



The Gibson inquiry was abandoned when Scotland Yard announced it was launching a criminal investigation into the UK’s involvement in the rendition in 2004 to Tripoli - where they were tortured - of Abdel Hakim Belhaj and Sami al-Saadi, militants opposed to the Libyan dictator Muammar Gaddafi.



“There are serious allegations of UK involvement in rendition in relation to the two Libya nationals. These would plainly require investigation”, said Gibson.

The results of an investigation by Scotland Yard, which began four years ago, is sitting in a file in the Crown Prosecution Service.



Further evidence of MI5 and MI6 involvement in the rendition of 16 prisoners to Guantanamo Bay was suppressed when they were offered compensation, amounting in some cases to about £1m, in return for dropping their attempts to sue British ministers and intelligence agencies in the courts.



The ISC, which admits its past investigations have been inadequate, will now undertake a new one, under its new chair, the former attorney general Dominic Grieve.



Kat Craig, legal director of tghe human rights charity, Reprieve, said: “The problem is that the government is dragging its feet on every front when it comes to accountability for these appalling events. Both government ministers and prosecutors seem to hope that if they just keep quiet about all this then it will go away.”



The former director of public prosecutions, Lord Macdonald of River Glaven, said it was now a question whether the intelligence services could be trusted to come clean about what went on during the war on terror.