The New York-based Center for Constitutional Rights (CCR) says the strike was set off in part by alleged beatings of prisoners by US troops, denial of basic needs, and lack of fair trials. They also estimate that up to 210 prisoners may be taking part.
The strikers say they are determined to die in the protest over the conditions. CCR, a legal aid group which is representing the prisoners at Guantanamo, in Cuba, said in a report released yesterday that they are demanding that authorities adhere to Geneva Convention standards of treatment of civilian detainees.
In statements obtained by The Guardian, a former London schoolboy, Binyam Mohammed, said: "I do not plan to stop until I die or we are respected. People will definitely die.
"Bobby Sands petitioned the British government to stop the illegitimate internment of Irishmen without trial. He had the courage of his convictions and he starved himself to death. Nobody should believe for one moment that my brothers here have less courage."
The hunger strike began on 8 August, according to military officials. Ten prisoners are being fed through nose tubes but are in a "stable" condition, according to Sgt Justin Behrens, a spokesman at the prison.
The strike is the latest in a series held since 2002 amid protests over treatment of prisoners.