One of the five Britons freed from Guantanamo Bay has said he received "horrific" treatment while he was detained by the US government.
About 600 people are still being held at Guantanamo Bay
Tarek Dergoul, 26, from east London, said he was held in inhuman conditions, interrogated at gunpoint and beaten.
The family of the 26-year-old believe his mental health has been "severely affected" by his experiences.
Another freed Briton, Jamal Udeen, has also complained of poor treatment at the Cuba camp, which the US denies.
Mr Dergoul, from Bethnal Green, was arrested two years ago in Afghanistan on suspicion of terrorism.
He was one of five Britons released by the US on Tuesday. Four are still being held at the camp in Cuba.
After returning to the UK, former care worker Mr Dergoul was freed without charge from British police custody on Wednesday.
In a statement released through his solicitor Louise Christian, he said "horrific things" had happened to him during detention at Bagram, Kandahar and Guantanamo Bay.
"This has included... botched medical treatment, interrogation at gunpoint, beatings and inhuman conditions," it said.
He accused the US and UK governments of "gross breaches" of human rights and demanded the immediate release of all the other detainees at Guantanamo Bay.
"Tarek finds it very difficult to talk about things and his family believe his mental health has been severely affected by the trauma he has suffered," the statement added.
US Secretary of State Colin Powell, in an interview with Sir Trevor McDonald for ITV1's Tonight
programme on Friday, dismissed the Britons' claims of mistreatment.
He said: "We have watched Guantanamo Bay very carefully knowing of the
interest of a number of nations, including the United Kingdom, and knowing that
we have responsibilities under the Geneva Convention and because we are
Americans, we don't abuse people who are in our care."
Mr Powell said it was "not in the American tradition to treat people in that
The other three Britons who were released are Ruhal Ahmed, 22; Asif Iqbal, also 22, and 26-year-old Shafiq
Rasul, who are all from Tipton in the West Midlands.
The four remaining at Guantanamo Bay are Feroz Abbasi, 23, from Croydon, south London, Moazzam Begg, 36, from
Sparkhill, Birmingham; Martin Mubanga,
29, from north London, and Richard Belmar, 23, from
Maida Vale, London.