The last Briton held in Guantanamo is "falling apart at the seams" and could die without ever being charged with an offence or meeting his youngest son, his lawyer has said.
Clive Stafford Smith made the claims after visiting Shaker Aamer, a British resident who despite being cleared for release in 2007 has languished in the prison in Cuba for a decade without ever being charged.
On the 10-year anniversary of the first prisoners arriving at the naval base, The Independent can also reveal:
* The UK Government has spent £274,345 fighting Mr Aamer in court, including preventing his lawyers viewing evidence that may prove his innocence
* The UK "misjudged" the US government's stance on Mr Aamer and gave false hope to his family
* Mr Aamer has several serious medical complaints and has been held for years in "inhumane" conditions away from other prisoners.
"This is a guy who has spent 10 years in US custody and been abused as horribly as anyone in Guantanamo. It would take an enormous toll on anyone. He is a human being who is gradually falling apart at the seams," said Mr Stafford Smith, who represents Mr Aamer in the US.
The lawyer, who saw his client in November, added: "He could die there... not many people would get 10 years in prison for a murder they did commit, let alone 10 years in jail without charge."
David Remes, another of Mr Aamer's US lawyers, said his client and a small number of detainees had been kept separately at a special part of Guantanamo named Camp Echo.
"The men were being held in cruel, inhumane, and degrading conditions... in violation of Geneva Conventions. Life was miserable for these men on every level, and completely different from how other detainees were being treated in the main camp," he said.
The British government has fought in the High Court since 2009 to prevent Mr Aamer's lawyers gaining access to evidence which may have proved his innocence. A Freedom of Information request revealed that £274,345 was spent on paying Treasury solicitors and counsel's fees and costs for managing the civil case. Eventually his legal team were allowed access.
Attempts were made to transfer him to Saudi Arabia, which would have enforced his separation from his wife and children and likely resulted in another spell in prison, but his refusal to go only led to him remaining in Guantanamo. "I am not willing to spend any time in Saudi Arabia for I have not been doing anything wrong to be in this evil place," he wrote to his wife in 2008.
Gareth Peirce, Mr Aamer's UK lawyer, said 10 years in prison without charge represented a "truly terrible milestone". "We remain completely sure that had the British government, past or present, exerted themselves in any energetic or convincing way insisting he be returned, he would be back. We put responsibility on successive UK governments," she said.
"The Coalition Government suggested they would be different and vigorous and they would succeed. They were assuring his family they were expecting to be successful. The promises of the last year have proved to be misjudged," Ms Peirce added.
An FCO spokesman said Mr Aamer's release had been raised again with US Secretary of State, Hillary Clinton, in December. He added: "We remain committed to securing the release of Mr Aamer, but ultimately it is a decision for the US authorities."
Defending the money spent on the High Court action, he said: "The Foreign Secretary has made it very clear how important it is for the UK's national security that the UK and US are able to share information in confidence."