Updated

More Guantanamo Bay detainees protesting their indefinite confinement joined a hunger strike, raising the number of inmates refusing food to 89 from 75, the U.S. military said Thursday.

Six of the hunger strikers at the isolated U.S. naval base in southeast Cuba were being force-fed, said Navy Cmdr. Robert Durand.

Defense lawyers have said the strike, which began last year, reflects increasing frustration among men who have little contact with the world outside the remote prison.

The military did not release the names of the striking detainees, and lawyers said they have no way of learning whether their clients are involved until they can visit the base.

Durand said the number of hunger strikers reached about 75 over the weekend. U.S. officials classify detainees as being on hunger strike when they have missed nine consecutive meals.

Some detainees began the strike last August to protest their confinement, with their number peaking at 131 in the fall, according to the military. Defense lawyers have said the military has underreported the number of hunger strikers.

Military officials believe the increase in hunger strikers was timed to coincide with the arrival of media and lawyers for the next round of pretrial hearings for Guantanamo detainees this month, Durand said.

He added that it also could be related to the clash in May in which a detainee pretended to commit suicide to lure guards into a cellblock, where they were attacked by detainees armed with makeshift weapons, according to the military.

Earlier that day, two detainees overdosed on antidepressant drugs they collected from other detainees and hoarded in their cells. The men have since regained consciousness.

The United States holds about 460 detainees at Guantanamo on suspicion of links to Al Qaeda or the Taliban. Ten have been charged and face military tribunals. The U.S. Supreme Court is expected to rule in June on whether President George W. Bush overstepped his authority by ordering military tribunals for some of those held at Guantanamo Bay.