Mr Mohamed, a British resident, claims he was tortured in US custody
In a BBC interview, Binyam Mohamed has revealed grim insights into his six years in captivity.
He said he was flown around the world on rendition flights and tortured in secret prisons in an ordeal which has left him feeling "dead" inside.
He also described his sudden release from Guantanamo Bay just over a fortnight ago, saying guards there told him to take a shower and within an hour he was on a plane back to the United Kingdom.
He said that when it touched down at RAF Northolt in London, that was the moment he finally realised he was free.
But he added that, until the US declares an end to its "war on terror", he will not feel safe.
'The real Islam'
Mr Mohamed is receiving medical care to help him cope with the aftermath of his ordeal and said there is a 60% chance of a full recovery.
The 30-year-old, who was born in Ethiopia, arrived in the UK in 1994 and sought asylum on the basis of his family's opposition to the Ethiopian government.
He said he travelled to Afghanistan in 2001 to escape a bad drug habit and because he had been told it was a place where the "real Islam" was being practised.
"I decided to take the journey to Afghanistan as any 21-year-old would do, just go and see part of the world and learn about what's happening over there," he said.
"And that's the reason I went to Afghanistan, just for exploration; it wasn't for nothing else."
The US authorities originally claimed he went to attend terrorist training camps and had met senior al-Qaeda leaders to discuss plots to target the West.
All charges against Mr Mohamed were dropped last year.
His legal representative would not allow him to answer questions about the false passports it is claimed he travelled on or about the training camps he is said to have attended.
Mr Mohamed said he was recovering in hospital from malaria when the 9/11 attacks took place and heard about it through word of mouth. He claims it took him several months to then escape from Afghanistan because the country was in a state of turmoil following the start of aerial bombardments.
He was arrested at Karachi Airport by immigration officers and said he was then handed over to Pakistani intelligence, whose officers began beating him.
Mr Mohamed believes that, having released details to the media in early 2002 of an alleged plot to use a dirty bomb in the US, the authorities there tried to falsely implicate him.
He said this was a "fantasy" and in their desperation to pin charges on him they brought Britain's MI5 security service in to help.
He claims he was eventually rendered to Morocco and he makes a series of highly damaging allegations against the British government concerning the information he claims they fed to his alleged torturers in Morocco.
He told the BBC: "They just done what I never thought would have been possible to do to another human being."
He said most of the questions asked there were about Britain and included inquiries about his kickboxing trainer in London and his college grades.
Among the hundreds of photographs of men he was asked to identify, he says there were CCTV images of people entering mosques.
"These photos were coming in maybe every three weeks and the torture was going on sometimes weekly, sometimes monthly… there was no routine to what was happening."
Foreign Secretary David Miliband has said that Britain neither practises nor condones torture but has said that claims that British agents were involved in torture will be investigated.
This week, Conservative leader David Cameron called for a "judge-led inquiry".
Mr Mohamed's view on the subject is that justice will in part be served by placing on trial "whoever signed the documents for my rendition".