SAN JUAN, Puerto Rico (AP) – A hunger strike at the U.S. prison for terror suspects in Guantanamo Bay, Cuba, has grown to its largest point since detainees began their latest protest more than a month ago, a military official said Thursday.

After 11 detainees joined the protest overnight, there are now 131 taking part in the hunger strike, said Maj. Jeff Weir, a spokesman for the detention center.

Twenty-one of the striking prisoners were hospitalized in stable condition at the prison medical clinic, including 20 who were being tube-fed, Weir said.

The military considers a hunger strike to be a form of suicide and Weir said that one prisoner was restrained after he resisted having a feeding tube inserted.

“No facility in the U.S., and hopefully the world, is going to let someone starve to death,” Weir said. “We’re charged with keeping them in good health, and that’s what we’re doing.”

Guantanamo officials said this latest hunger strike began Aug. 8 with 76 detainees protesting their confinement. It has since grown to more than a quarter of the approximately 500 detainees.

The military defines someone as being on a hunger strike after they have refused nine consecutive meals. There have been at least two previous hunger strikes, but military officials said they were not able to confirm whether this was the largest.

A U.S. human rights group, the New York-based Center for Constitutional Rights, has claimed that some 210 detainees are participating in the hunger strike.

The center said the prisoners are angry because the military allegedly reneged on promises to bring the prison into compliance with the Geneva Conventions if prisoners agreed to end a hunger strike that began in June.

The military has denied it reneged on any promises. It says detainees have chosen representatives to meet with military officials about living conditions at the camp.

The detainees are accused of ties to the al-Qaida terror network or Afghanistan’s ousted Taliban regime. Most have been held for more than three years without charge.