Binyam Mohamed came to the UK as an asylum seeker in 1994
A British resident facing a military trial in Guantanamo Bay has launched a legal attempt to make the UK government release evidence for his defence.
Lawyers acting for Binyam Mohamed, who was detained in Pakistan in 2002, say the government has proof that his testimony was obtained under torture.
They are also seeking evidence he was subjected to "extraordinary rendition" - transport abroad for interrogation.
Mr Mohamed's legal team say he could face the death penalty if convicted.
They lodged papers at the High Court in London on Tuesday seeking a judicial review.
Mr Mohamed was detained in April 2002 as he tried to return to the UK from Pakistan.
He says he was taken from there to Afghanistan and Morocco for questioning before being transferred to Guantanamo Bay in Cuba.
His lawyer, Clive Stafford Smith, said it had been established that Mr Mohamed was questioned by British intelligence for three hours in Pakistan.
Mr Mohamed says a British security service officer indicated to him that he was to be taken to an Arab country - something his lawyers say proves British authorities knew of a rendition plan.
Mr Stafford Smith wants details of this interview to be released.
He is also seeking access to flight records from the UK-dependent territory of Diego Garcia, which he says could establish that planes used for "extraordinary rendition" refuelled there.
And he says the government has proof that Mr Mohamed's genitals were repeatedly slashed with a razor blade while he was being held in Morocco.
Mr Stafford-Smith said on Tuesday: "The issue here is whether the British government has an obligation to help us, as Mr Mohamed's lawyers, prove that torture evidence has been extracted from him and that is effectively the only evidence that the US military is trying to use to convict him.
"The real issue here is some magnet of fear that has drawn the moral compass of the UK government far from the direction of human rights."
The US government has insisted the military tribunals at Guantanamo are fair, but critics disagree.
They say the standard of proof required to convict is much lower and those on trial only have limited access to the evidence used against them.
Mr Stafford Smith said the matter was now urgent as he understood charges against his client were "imminent".
Mr Mohamed came to Britain as an asylum seeker in 1994, when he was 16.
Although his asylum claim was never finally determined, he was given leave to remain, and went on to work as a cleaner in west London.
But in 2001 he travelled to Afghanistan and Pakistan, where he was later detained.