Bisher al-Rawi, 37, who has lived in Britain for more than 20 years, says that he was working for British Intelligence when he was picked up by the CIA during a trip to Africa.

Lawyers for Mr al-Rawi and two other long-term British residents held at Guantanamo claim that they are all being tortured and want the High Court to order Jack Straw, the Foreign Secretary, to lobby the US authorities for their release.

The Government has said that as foreign nationals the men have no legal right to the assistance they are demanding.

But the Foreign Office said yesterday that Mr al-Rawi’s case was now regarded as different. “The Foreign Secretary considered it appropriate to reconsider Mr al-Rawi’s request that he make representations to the US,” it said.

Mr al-Rawi, an Iraqi national, and his Jordanian business partner, Jamil el-Banna, who was granted refugee status in 2000, were picked up in Gambia three years ago and accused of trying to set up an al-Qaeda terrorist training camp. Both men claim that they were asked by British Intelligence to infiltrate an organisation run by a London-based radical cleric, Abu Qatada.

Timothy Otty, who is appearing for the detainees, said that documents from a security service agent, “Witness A”, established that there were “communications” relating to the two men before their arrest in November 2002, between the British and US security services.

The third man, Libyan-born Omar Deghayes, 36, had also been held at Guantanamo for three years and was now on a hunger strike, Mr Otty said.

The hearing is expected to last for two more days.

Explore Law

• Corporate Law

• Public Law

• Columnists

• Law Panel

• Student Law

• Law Reports

Times Recommends

• PM to sue Icesave to get savers' money
• Former UBS lawyer pays $6.5m to settle probe
• Test case over non-dom told to pay UK taxes