Shaker Aamer, a 46-year-old inmate from London, told a lawyer at the prison last week authorities have taken up new tactics to try and end the hunger strike, The Guardian reported.
Such tactics include making cells "freezing cold," Aamer said, and using "metal-tipped" feeding tubes, which force inmates vomit on themselves.
"The administration is getting ever more angry and doing everything they can to break our hunger strike. Honestly, I wish I was dead," Aamer said.
Clive Stafford Smith, the director of the legal charity Reprieve, handed the transcript of his conversation with Aamer to the newspaper the Observer, and said: "These gruesome new details show just how bad things are in Guantanamo. The whole thing is at breaking point. Clearly the U.S. military is under enormous pressure and doing everything it can to hurt the men and break the hunger strike."
Aamer has been held at Guantanamo Bay for 11 years without trial.
British Prime Minister David Cameron spoke to U.S. President Barack Obama about Aamer's case During the G8 summit in Northern Ireland Wednesday. Cameron says he will write to Obama about the "specifics of the case and everything that we can do to expedite it."
"Clearly, President Obama wants to make progress on this issue and we should help him in every way that we can with respect to this individual."
The United States, which initially denied reports of a hunger strike at the prison, said 104 of the 166 inmates at Guantanamo are on a hunger strike, and 44 of them are being force-fed.