Two leading psychiatrists say Sami al-Hajj, the Al Jazeera cameraman held in the US prison camp at Guantanamo Bay in Cuba, is suffering from severe depression and could be close to death.
The British and American psychiatrists said in a letter that al-Hajj, who has been on hunger strike for 247 days, could be suffering from a form of depression known as "passive suicide", where an individual loses the will to live.
Psychiatrists Hugh Richards from Britain and D L Crisson from the US warned on Tuesday that if al-Hajj remained in the camp, his life could be in danger.
Clive Stafford-Smith, al Hajj's lawyer, told Al Jazeera: "I'm incredibly worried about him.
"Last time I saw him ... he was talking about death."
Al-Hajj, originally from Sudan, was arrested in Pakistan in December 2001 on the Afghanistan-Pakistan border by Pakistani intelligence and was handed to the US military in January 2002.
The cameraman is one of about 20 prisoners in Guantanamo Bay who have carried out a hunger strike in protest at their imprisonment and treatment at the US detention centre in Cuba.
In July, al-Hajj had reportedly lost 18kg in weight since he began the hunger strike, according to notes from a meeting with his lawyer.
Stafford-Smith said the US military was behaving shamefully by force-feeding hunger strikers.
Al-Hajj has also complained that hunger strikers at Guantanamo were stripped of all their personal items except their clothes and had only a thin mat on which to sleep.
The two psychiatrists said in their letter that al-Hajj was in a constant state of fear and anxiety and felt that he was being pursued and could be killed.
The two said al-Hajj needed immediate treatment from specialised doctors to alleviate his condition.
The cameraman, who has been accused by the US of having links to al-Qaeda, could be released if Khartoum guarantees that he remains in Sudan.
However, negotiations over his release stalled in August and Stafford-Smith urged the authorities in Qatar, where Al Jazeera is based, to intervene on behalf of their employee.