They reveal that MI6 and the CIA had a regular dialogue with their counterparts in Libyan Intelligence, in particular Musa Kusa the former head of Libya´s intelligence service and foreign minister who defected to the UK earlier this year.

Kusa flew to Britain in March and was allowed to fly to Qatar the following month, despite being accused of rights violations.

The papers reportedly include letters and faxes to him headed ´greetings from MI6´ and a personal christmas greeting signed by a senior spy as ´your friend´.

The New York-based Human Rights Watch said that the documents were apparently found in Musa Kusa´s former offices in Tripoli.

Human Rights Watch emergencies director Peter Bouckaert said his organisation ´stumbled across a room containing the files´.

He said they expose the ´close relationship´ between Kusa and the CIA and MI6.

´These documents we found, their faxes start off ´Dear Musa, thanks for the oranges you sent us, they were delicious´,´ he said.

One file reportedly details the UK´s help in drafting a speech for Colonel Gaddafi to make.

Another document apparently shows that a statement given by Col Gaddafi saying that his regime was giving up weapons of mass destruction was put together with the help of British officials.

Another contains information on Tony Blair´s meeting with the former Libyan Leader in 2004 and suggests it was Downing Street´s idea for the two men to meet in a tent.

´No 10 are keen that the Prime Minister meet the Leader in the tent,´ a letter from an MI6 officer says.

Also among the files is evidence that the United States used Libya as a base for its rendition programme - transporting prisoners it believed to be a threat to its national security for further interrogation on foreign soil.

Human rights organisations claim that the real purpose was to torture these prisoners outside of US jurisdiction.

Bouckaert said the documents about alleged CIA renditions to Libya included some on the man who is now head of the Tripoli Military Council, Abdel-Hakim Belhaj.

´He was captured, abducted together with his pregnant wife and flown on the so-called black flight to Tripoli for his interrogation,´ Bouckaert said.

There is no suggestion that the UK was involved in the rendition process but there are allegations from the secret papers that UK intelligence gave its Libyan counterparts information on dissidents to the Gaddafi regime who were living in Britain at the time.

´Libya asked the US to send Abu Abdullah al-Sadiq, an opposition leader, to Libya and a CIA case officer wrote back in March 2004, that ´we are committed to developing this relationship for the benefit of both our services,´ and promised to do their best to locate him, according to another document.´