Four are so ill that they lie in shackles in the hospital wing and insiders predict it is only a matter of time before one perishes.
"It is possible that I may die in here," said the last Briton inside, Shaker Aamer, 44, through his lawyer, Clive Stafford Smith, recently. "I hope not, but if I do die, please tell my children that I loved them above all else, but that I had to stand up for the principle that they cannot just keep holding people without a trial, especially when they have been cleared for release," said the father of four, who remains in Camp 5 despite being approved for release more than five years ago. "Sad to say, torture and abuse continue in Guantanamo Bay and the US is throwing away yet more of its dwindling moral authority," added Stafford Smith.
The protest, which began on February 6, has now spread through Camp 6 and Camp 5 with an estimated 100 to 130 taking part. These are not the high value detainees kept in Camp 7, the handful charged with terror offences. The hunger strikers are those who have waited a decade or more without trial, including 86 cleared for release, but remain trapped because of restrictions imposed by Congress.
As President Barack Obama pledged to press for Guantanamo's closure last week, detainees described how it has gone back to the draconian regime of the Bush Administration.
"Defence lawyers have tried to engage in constructive dialogue but we have been met with resistance and silence," explained US Army Captain Jason Wright, a lawyer who described seeing his client Obaidullah, now a 52kg "bag of bones", a few days ago as "extremely distressing".
"When I walked into the room he was demonstrably changed. He said, 'They won't treat us with dignity, they are treating us like dogs'. There is an urgency. It is clear that if this hunger strike continues there will be deaths. These men are going to die in this prison for nothing. It is an absolute outrage," said Wright.
The protest began when, according to lawyers, the new administration decided to end "an era of permissiveness" and take a more punitive approach, in contravention with the Geneva Convention, which calls for preventative detention. Guards confiscated all "comfort items" but what inflamed inmates most was a search of their Korans, an act the administration denies.
First-hand reports reveal that most prisoners are now being held in solitary confinement in empty, windowless cells just 3.5m by 2.5m. Clean water is rationed, they say, and they have been stripped of all possessions.
They complain the air-conditioning has been turned up to an icy level, guards deliberately disturb prayer times and turn up throughout the night to take them for showers.
Describing sleeping on a concrete floor, using his shoes as a pillow, Moroccan Younous Chekkouri said via phone to his lawyers at the charity Reprieve: "Pain starts immediately when I'm on the floor. Pain in my neck, pain in my chest. Finally at night they gave us blankets. It was very cold. Water is now a privilege. They are treating us like animals," he added. "I thought my torture had ended, but what is happening now is horrible."
Amnesty was among several human rights organisations to describe the situation at the camp in Cuba as "at crisis point" while UN special rapporteur on torture Juan Mendez condemned the continued detention as "cruel, inhuman and degrading".
Omar Deghayes, 43, a British resident who was released without charge in 2007, recalled the effect of two shorter hunger strikes. Lying in a "fridge-like" cell, he said he could barely stand within four days and was consumed with hunger and pains.
"You start to hallucinate. When people talk to you, you can't understand them. I started to hear voices. Then I started to vomit blood and puss. Your stomach contracts and when they force feed large quantities, you can't control anything, you get diarrhoea on your trousers. They take you into the yard and hose you down."
The Department of Defence said it used enteral feeding only when a detainee's life was in danger. Lieutenant Colonel Todd Breasseale added detainees had the highest standards of humane treatment.
"Detainees are not punished for hunger striking. However, we will not allow them to harm themselves," he said, adding: "We will not allow them to commit suicide by starving themselves to death."
Dr Jeremy Lazarus, president of the American Medical Association, wrote to Defence Secretary Chuck Hagel recently to complain that force feeding was in violation of medical ethics.
"I can't imagine they understood what they are being asked to do for their country," he said. "I hope some of them have the courage to say no."
- Independent