A month-old hunger strike at the U.S. military prison at Guantanamo Bay, Cuba, has grown to include at least 128 detainees, 18 of whom are forcibly receiving intravenous fluids or nutrition in the prison hospital, military officials and detainee lawyers said yesterday.

The captives are protesting their indefinite imprisonment and what they describe as beatings administered by the prison's Immediate Response Force (IRF) -- squads of military personnel who are dispatched to put down disturbances in detainees' cells. Some have said they will refuse to eat until the military gives them a fair hearing or they die, according to their attorneys.

Military officials first acknowledged the hunger strike, the second of the summer, on Aug. 25. Since then, the number of people hospitalized and in serious physical danger has grown to 18, according to Maj. Jeffrey J. Weir, a Guantanamo Bay spokesman. He said that step was taken to prevent any of the approximately 520 prisoners at the U.S. Navy base prison from engaging in a "form of suicide."

The hunger strike began in the first week of August, and, according to newly declassified accounts of detainees provided by their lawyers, has gradually spread across several camps at the prison. Detainees allege they have been severely beaten and are deeply frustrated at their indefinite detentions. Some have been held for 31/2 years without facing charges.

Lawyers for the prisoners assert that more than 200 detainees are refusing food. An earlier hunger strike in June and July ended after military authorities met with a small group of detainees and promised improvements in their living conditions.

"They truly feel they have nothing left," said attorney David Remes, who represents several Yemeni detainees. "I'm not sure what the end point will be. But I do predict there will be death."

Binyam Mohammed, formerly of London, whose account was the first declassified, told his attorney on Aug. 11 of the new hunger strike. "I do not plan to stop until I die or we are respected," he said. "People will definitely die."

Another detainee, Libyan-born Omar Deghayes, told his lawyer he had not eaten in five weeks. "Many more people have fallen unconscious. . . . More are taken to hospital," he said.

Military officials have characterized the protest as a "fast" of prisoners aimed at grabbing attention, and say it involves 128 prisoners. They say its significance is exaggerated by their lawyers.

Weir said no detainees are in danger of dying and that the military's treatment is preventing them from losing critical nutrition. Of the 18 people hospitalized, 13 are being force-fed through nasal tubes and five are being given intravenous hydration.

On Aug. 25, the military said that 89 detainees were fasting and seven were hospitalized and receiving forced fluids or nutrition.

Weir said yesterday that the military does not allow beatings of detainees, and he believes the refusal to eat is part of a campaign to press for their transfer or release.

"My understanding is that it's just because of their continued detention," Weir said. "They're trying to call attention to that."

The majority of detainees at Guantanamo Bay have long insisted that they were captured by mistake by U.S. forces in Afghanistan in the fall of 2001. In some prisoners' cases, records show, the military has little but circumstantial evidence that the men engaged in or supported terrorist acts. The military's review of 558 cases resulted in 38 detainees being declared non-enemy combatants.

The appellate court for the District of Columbia heard arguments last week on the legality of the military holding the detainees indefinitely without giving them the chance to challenge their detentions in a U.S. court -- a follow-up to a U.S. Supreme Court ruling in 2004. But that dispute is expected to drag on until next year, and is likely to be appealed to the Supreme Court again.

Hunger strikes are not new to the prison. Detainees launched one in 2002 after allegations that guards and interrogators mistreated copies of the Koran. Military officials then issued new guidelines for proper treatment of the Islamic holy book, and the strike ended.

Detainees began a new strike in late June to protest their treatment and the quality of their food and water. They complained about solitary confinement, alleged beatings by IRF teams, and the use of uniform colors to signify how detainees should be treated. Detainees given white uniforms are considered cooperative while those assigned orange uniforms are considered uncooperative and treated more harshly, detainees said.

The prisoners halted the previous strike in the first days of August after military camp leaders met with a small "council" of detainees and promised improvements in their living conditions. But the strike resumed a few days later, some detainees told their lawyers, when news spread through the camp of a Tunisian detainee beaten by an interrogator and IRF teams hitting two others, according to detainees' reports to their lawyers.

Weir declined to discuss individual detainees' cases or allegations.

An Algerian detainee told his lawyer in a newly declassified report provided by his attorney that a new interrogator beat the Tunisian with an empty beverage cooler and a metal chair after the detainee refused to talk to him. The Algerian said he saw the Tunisian's bloodied, swollen eye after the session.

Weir declined to comment on those details. Other detainees' accounts of the strike have not yet been declassified by the military, their lawyers said.

Researcher Julie Tate contributed to this report.

A sentry surveys the compound at Guantanamo Bay, Cuba. As many as 200 of the prisoners may be on a hunger strike.