US military officials say eighty-four suspects are currently on a hunger strike including 46 detainees "that have refused nine consecutive meals since December 25."
"The number of detainees engaged in the current fast, which began on August 8, 2005, routinely fluctuates," said a statement from the US Joint Task Force at Guantanamo Bay.
Australian detainee David Hicks is not believed to be part of the hunger strike.
The prisoner population, which the Pentagon says numbers about 500, is believed to be uniformly Muslim. Only nine have been charged with any crime.
The number peaked in September, when 131 inmates were on a strike, according to news reports.
"Since then, increases in the number of fasters have coincided with the anniversary of the September 11, 2001 terrorist attacks and the scheduled arrival of defence attorneys representing certain detainees."
Lawyers for some of the detainees call the strike a protest of the conditions in which the prisoners are being held and their lack of legal rights.
Medical personnel were force-feeding 32 of the hunger strikers with plastic tubes inserted into the stomach through through the nose, the military said.
Asked the purpose of the force-feeding Army Lieutenant Colonel
Jeremy Martin, a military spokesman said: "Because our policy is to preserve life."
Hunger striking "is consistent with Al-Qaeda training and reflects detainee attempts to elicit media attention," and to bring pressure on the US government "to release them," the statement emphasised.
Guantanamo Bay detention centre holds about 500 detainees, most of who were captured in Afghanistan in the fall of 2001.
Since opening in January 2002, the prison has been the focus of controversy over the indefinite detention of suspects without charges or legal representation, as well as accusations of torture and detainee mistreatment.
Hunger strikers "are closely monitored by medical professionals, receive excellent medical care, and when required, the appropriate amount of daily nutrition and hydration through enteral feeding," the statement read.
Detainees are willing to starve to death to demand humane treatment and a fair hearing on whether they must stay at the prison, their lawyers said.
Most of the detainees were captured in Afghanistan and have been held for nearly four years.