The last Briton to be released from Guantanamo Bay has demanded a full public inquiry into the security services after claiming British intelligence officers were complicit in his detention and torture.
Shaker Aamer gave his first TV interview to ITV News after being released from the controversial prison camp following 14 years in detention without charge.
Mr Aamer, a British resident who returned to England in October, claimed UK intelligence officers were present while he was being 'interrogated' - which he says included the use of physical violence.
A government spokesman said they "do not participate in, solicit, encourage or condone torture of any kind, for any purpose".
But Mr Aamer told ITV News he believes the officers may have operated outside of the knowledge of the government.
"It could be the intelligence services themselves sent them there without the knowledge of the British government," he said, adding:
He said one of them, who called himself 'John', even commented on his dramatic loss of weight - telling him he looked "like a ghost".
During his time in US detention at bases in Afghanistan and in Guantanamo Bay, Mr Aamer claimed he suffered regular beatings, was doused in freezing water, had his head smashed against a wall, was starved and deprived of water and made to stand for up to 18 hours at a time.
The guards would also hog-tie prisoners, he said - an experience he described as: "They tie your hands and your legs together, and you cannot relax because your hands are behind your back and you are curved. If you relax, you will be putting all your weight on your wrist and your legs."
It was the psychological torture he found hardest to bear, he said - including rock music blasted into cells when they knew prayer time was approaching.
"With no doubt the psychological one [is the worst part]. With no doubt," he said.
"Physical pain goes away.Once you get beaten up, once you get hanged, all these hog ties and all these things ... first day, second day, you get used to it.
"But when they try to play with you mentally and psychologically all kind of manipulation you feel like every time they find something new to do."
The father-of-four also spoke of his touching reunion with his family, revealing how he broke down in tears when he saw his children for the first time.
His daughter Johnina was just four when he was arrested, while her younger brothers Mikhail and Said were aged just two and one.
The youngest, Faris, was born the day he arrived in Guantanamo - and for more than 13 years, father and son did not meet.
Mr Aamer told ITV News his first instinct was to "grab them and hug them" - but said they were wary of the man who, for all intents and purposes, was a stranger to them.
Now, he said, he wants to focus on learning how to be a father - a skill he has not practised for more than a decade of his life.
Prime Minister David Cameron has previously ordered the Intelligence and Security Committee to investigate claims of UK complicity in rendition and torture at Guantanamo Bay.
ITV News correspondent Juliet Bremner reports:
A government spokesman said they do not "participate in, solicit, encourage or condone" torture of any kind, for any purpose.
Watch ITV News' extended interview with Shaker Aamer on our bulletins tomorrow