It comes after papers suggesting close ties between MI6, the CIA and the Gaddafi regime were found in Tripoli.

Sir Peter Gibson's inquiry into alleged involvement in torture by UK security agencies has said it will investigate.

A former Libyan foreign minister has claimed MI6 was co-operating with the old regime until about six months ago.

Meanwhile UK officials, including staff from the Foreign Office and Department for International Development, have arrived in Tripoli to re-establish a diplomatic presence in Libya.

Making a statement on Libya in the Commons earlier, Prime Minister David Cameron said: "We've asked the retired judge, Sir Peter Gibson, to examine issues around the detention and treatment of terrorist suspects overseas and this inquiry has already said it will look at these latest accusations very carefully.

"My concern throughout has been not only to remove any stain on Britain's reputation but also to deal with these accusations of malpractice so as to enable our security services to get on with the vital work that they do."

Opposition leader Ed Miliband said he agreed with the prime minister "that the Gibson inquiry must get to the bottom of the allegations".