Updated

The number of Guantanamo Bay detainees staging a hunger strike spiked suddenly from 3 to about 75, the U.S. military said Monday, describing growing defiance among men who have been held for up to 4 1/2 years with no end to their imprisonment in sight.

Navy Cmdr. Robert Durand said the detainees' hunger strike on the U.S. naval base in southeast Cuba was an "attention-getting" tactic aimed at securing their release and may be related to a May 18 clash between detainees and guards that left six detainees injured.

"The hunger strike technique is consistent with Al Qaeda practice and reflects detainee attempts to elicit media attention to bring international pressure on the United States to release them back to the battlefield," Durand said from Guantanamo Bay.

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

"I think it is escalating because the people down there are getting more and more desperate," said Bill Goodman, legal director of the New York-based Center for Constitutional Rights, which represents many of the detainees. "Obviously, things have reached a crisis point."

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.

"All these men want is a chance to have a trial," said Zachary Katznelson, an attorney for Reprieve, a British human rights group that represents 36 Guantanamo detainees. "If they are guilty, punish them. If not, then send them home."

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 76 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.

The attorneys say the number of strikers dwindled to three earlier this year after the military adopted more aggressive measures to force feed them, including using a restraint chair. U.S. officials said the measures were "safe and humane" and have been used in American civilian prisons.

Four of the detainees on hunger strike are being force-fed, including the three who were participating in the protest before the recent increase, Durand said.

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 in June, Durand said.

He added that it also could be related to the clash earlier this month 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.