Lawyers for three former UK residents held at Guantanamo Bay are seeking a court order to get the Foreign Office to press for their release. Amnesty International says at least eight men who have lived for years in Britain are held at the US detention camp.
The UK government has not pursued their cases because the men never took British citizenship.
Some 500 people remain incarcerated at the Cuban jail
Foreign Secretary Jack Straw has said that under international law the government can only take up consular matters in respect of British citizens.
Last month, a judge said claims of torture at the camp meant the government might have an obligation to act on their behalf.
The men's solicitor Gareth Peirce called the ruling "the first ray of light that we have had".
Bisher al-Rawi, 37, of London
Businessman Bisher al-Rawi is an Iraqi citizen with UK residency.
He was arrested, along with his Jordanian business partner Jamil al-Banna, at Banjul airport on a business trip to Gambia in November 2002 on suspicion of links to terrorism.
Their lawyer Rabinder Singh has said these arrests were "far from any theatre of war".
The pair were moved to Guantanamo Bay early in 2003.
Mr al-Rawi reportedly came to England in 1985 after his father was arrested by Saddam Hussein's secret police.
He has lived in the UK for nearly 20 years. His immediate family are UK nationals, but he retained Iraqi citizenship to preserve a link to their homeland.
Jamil el-Banna, late 30s, of north-west London
Jamil el-Banna, who had been living in north-west London, is a Jordanian with refugee status in the UK.
He has also been detained in Cuba since early 2003 following capture in Gambia in November 2002.
The father-of-five has never seen his youngest daughter who was born in April 2003.
Amnesty argues that the UK is obliged under international refugee law to make representations on his behalf.
Mr el-Banna's case has been taken up by his Brent East MP, Sarah Teather.
Omar Deghayes, 36
Libyan-born Omar Deghayes, 36, grew up in Brighton and studied law at British universities. He wanted to be a human rights lawyer, says Amnesty.
He was granted refuge status with his family in the 1980s and has been held at Guantanamo for more than three years, the campaign group said.
Mr Deghayes was arrested in Pakistan before being transferred to Cuba.
Amnesty says he had applied for citizenship but missed an interview because he was abroad.
He is accused of committing terrorist acts against the United States, but his lawyers claim it is a case of mistaken identity.
His lawyers claim he has been rendered virtually blind by the use of pepper spray and the gauging of his eye during his detention, but is still constantly subjected to high light levels.
Shaker Abdur-Raheem Aamer, 39, of London
Shaker Abdur-Raheem Aamer, originally from Saudi Arabia, had been living in the UK since 1996.
He is reported to have travelled to Afghanistan in August 2001 to carry out voluntary charity work.
According to Amnesty, his wife heard from newspaper reporters in January 2002 that he had been captured.
Cuba detainee Shaker Aamer with his daughter Johina and son Michel
His first letter from Guantanamo Bay was dated 16 February 2002.
He had been applying for citizenship and had indefinite leave to stay in the UK when he was captured.
The Independent has reported that he lived in London with his wife and three children, all British citizens, and worked as an interpreter.
A fourth child has been born since his capture.
Benyam Mohamed al Habashi, 27
Benyam Mohamed al Habashi was born in Ethiopia but sought asylum in the UK in 1994 and was given leave to remain, says Amnesty.
The campaign group says after seven years in the UK he converted to Islam. He travelled to Pakistan and Afghanistan and was arrested by Pakistani immigration officials at Karachi airport in April 2002 while intending to return to the UK.
Last summer he was among Guantanamo detainees to go on hunger strike to protest against the conditions and their lack of access to a judicial review.
Ahmed Errachidi is a Moroccan who lived in London for 18 years, where is wife and two sons currently live, says Amnesty International.
The campaign group says he travelled to Pakistan on a business venture but went to Afghanistan to offer humanitarian help during the war. After his return to Pakistan he was captured by authorities and eventually taken to Guantanamo, it says.
Ahmed Ben Bacha
Ahmed Ben Bacha is an Algerian who was living in Bournemouth. His case has only recently been filed and little is known by Amnesty at this stage.
Abdulnour Sameur is from Algeria and lived in south Harrow, Greater London. He was given refugee status in 200, says Amnesty.