The UN has expressed concern at the government's decision to hand an independent inquiry into the UK's awareness of torture in foreign jails over to MPs.
An interim report by former judge Sir Peter Gibson, which was released last week, found that British intelligence officials were aware of the mistreatment of detainees.
But Cabinet minister Ken Clarke announced that the investigation would be taken up by the parliamentary Intelligence and Security Committee (ISC).
UN Special Rapporteur on torture Juan E. Méndez said:
It is particularly discouraging to know that the decision was handed over to the ISC which is known to have previously failed to fully investigate prior allegations of torture, ill-treatment, rendition and surveillance in the context of counter-terrorism and national-security.
A senior Conservative MP has said "it is truly shocking" that Britain helped the United States to kidnap and torture British detainees, as he warned that the Government would come to regret its decision not to allow an independent judge-led inquiry to run its course.
Andrew Tyrie said today's confirmation by Cabinet Office minister Ken Clarke that the investigation would instead be handed over to Parliament's controversial Intelligence and Security Committee (ISC) was "a mistake".
It is truly shocking that Britain has facilitated kidnap and torture. And the decision to end, to abandon this judge-led inquiry will, I think, come to be seen as a mistake.
What confidence can the public have in their conclusions when that same body wrongly concluded that Britain was not involved in 2007 only to be flatly contradicted by a High Court written ruling the following year?
Cabinet Office minister Ken Clarke said the report into the treatment of detainees "paints a picture" of Government and agencies struggling to adapt to the new realities faced in the wake of 9/11 and said it was a matter of "sincere regret" if "mistakes and failures were made".
It is now clear that our agencies and their staff were in some respects not prepared for the extreme demands suddenly placed upon them.
The guidance regulating how intelligence officers should act was inadequate. The practices of some of our international partners should have been understood much sooner.
Oversight was not robust enough and there was no mechanism in the civil courts for allegations against the security and intelligence services to be examined properly.
The Gibson report acknowledges the "extreme harshness" of the conditions and treatment of detainees in the so-called war on terror and it calls into question the conduct of British intelligence officers.
There is no evidence that UK intelligence officers were directly responsible for the mistreatment of detainees.
It does say British intelligence officers were aware of mistreatment but that "in some instances officers did not recognise or report treatment issues, which fell short of torture".
It also says British intelligence officers warned detainees they might face "negative consequences" if they did not cooperate.
The detainees took these kind of warnings as a threat.
Sir Peter Gibson said it was not always clear that government ministers were kept informed of mistreatment issues and he says the UK may not have known the full extent of the US secret rendition programme which moved detainees around the world.
There is evidence that UK intelligence officers were aware of inappropriate interrogation techniques and mistreatment of some detainees held in other countries, a new report has found.
Revealing the findings of the detainee inquiry in the House of Commons, Cabinet minister Ken Clarke said the report identified 27 issues requiring further investigation.
The inquiry was set up by David Cameron in 2010 to investigate whether Britain was implicated in the improper treatment of detainees held by other countries in the aftermath of the 9/11 terrorist attacks.
There was also evidence that the Government or its agencies may have become "inappropriately involved" in some cases of rendition.
Mr Clarke said allegations of illegal rendition have harmed the reputation of the UK and its security services.
The inquiry examined more than 20,000 documents with the majority highly classified material.
Sami al Saadi, the Libyan dissident who the Government has agreed to pay over his rendition, says he still doesn't know the truth. He said:
I started this process believing that a British trial would get to the truth in my case. But today, with the Government trying to push through secret courts, I feel that to proceed is not best for my family.
I went through a secret trial once before, in Gaddafi's Libya. In many ways, it was as bad as the torture. It is not an experience I care to repeat.
Even now, the British Government has never given an answer to the simple question: 'Were you involved in the kidnap of me, my wife and my children?
Cori Crider, the legal director of Reprieve, said the public had the right to know how and why the government became complicit in the rendition of families, including children and a pregnant women, to Libya.
Jack Straw must come clean with Mr Belhadj, Mr al Saadi and their families. They deserve an apology for the appalling way they were treated.
It is now also totally unreasonable for the Government 'neither to confirm nor deny' its role in the al Saadi and Belhadj renditions. Yet this is their official position. What is left to be covered up, besides the reasons these terrible mistakes were made? The case needs to be fully examined - in the open.