Moazzam Begg - the Birmingham Muslim once held in solitary confinement in Guantanamo Bay - yesterday accused America's top lawyer of lying about life in the camp.
The 37-year-old, who was held in Cuba for three years, said US Attorney General Alberto Gonzales's claim that prisoners had unprecedented legal protection was "utter nonsense".
Mr Gonzales was giving a speech in London in which he said detainees were well looked after and had state-of-the-art medical care, healthy meals, and their cultural and religious requirements were catered for.
He also insisted America was constantly reassessing whether the camp - which Tony Blair has called "an anomaly" - was effective and lawful.
He said all detainees were granted an assessment by US authorities, a right of reply and a separate, formal hearing of their case before a three-member tribunal with a right to appeal.
And he denied the treatment of some inmates amounted to torture - a point which Mr Begg, who was released from the camp in January of last year, agreed with.
"I wouldn't say I was tortured in Guantanamo Bay. I was tortured in Bagram, which was where I was held before, but not in Guantanamo Bay," he said.
"Certainly they have made changes in Guantanamo Bay since I was there. Since it came into the limelight, they have responded to world opinion a little more. Possibly the conditions are a little better.
"But the right to habeas corpus amounts to nothing. Habeas corpus means you either appear before a court or you are released.
"Nobody has ever been released from Guantanamo Bay as a result of going through a court. It has always been through diplomacy.
"To say detainees have legal protection is a complete joke," he said.
Mr Begg, who was born in Sparkhill, Birmingham, was detained by American troops in Pakistan shortly after September 11, 2001.
Tonight Channel 4 is screening The Road to Guantanamo, the film telling the story of three men from Tipton - Shafiq Rasul, Ruhel Ahmed and Asif Iqbal - who were held for two years at Camp X Ray and Camp Delta.
The film is being shown at 9pm.