The number of Guantanamo Bay prisoners taking part in a hunger strike that began nearly five months ago has surged to 84 since Christmas Day, the US military said.
Forty-six detainees at the prison for foreign terrorism suspects at the US naval base at Guantanamo Bay, Cuba, joined the protest on Christmas day, said military spokesman Army Lt Col Jeremy Martin.
The prisoner population, which the Pentagon says numbers about 500, is believed to be uniformly Muslim. Only nine have been charged with any crime.
"There's been a significant increase in the number that have been added to the hunger strike," Lt Col Martin said.
Medical personnel were force-feeding 32 of the hunger strikers with plastic tubes inserted into the stomach through the nose, the military said. Asked the purpose of the force-feeding, Lt Col Martin said, "Because our policy is to preserve life."
Military officials define a hunger striker as a detainee who has refused nine straight meals, and often refer to the strike as a "voluntary fast" and force-feeding as "enteral feeding."
The detainees began the strike in early August after the military reneged on promises to bring the prison into compliance with the Geneva Conventions, their lawyers said.
Detainees are willing to starve to death to demand humane treatment and a fair hearing on whether they must stay, the lawyers said. Most of the detainees were captured in Afghanistan and have been held for nearly four years.
Amnesty International official Jumana Musa said this week's surge illustrates the strike's seriousness.
"You are talking about a prison population of hundreds who have decided that with no conceivable change in their future that they just don't care to live anymore, or they are going to make a statement in dying," Ms Musa said.