San Juan: Three detainees at Guantanamo Bay hanged themselves using nooses made from sheets and clothes, in what are the first reported deaths at the prison in over four years.

Military officials have said the suicides were coordinated. Two Saudi men and one from Yemen were found dead shortly after midnight on Saturday in separate cells. Attempts to revive the men were unsuccessful.

US president George W Bush, who was spending the weekend at Camp David, expressed "serious concern" over the suicides, White House press secretary Tony Snow said on Saturday evening.

Base commander Navy Rear Adm. Harry Harris said, "They have no regard for human life, neither ours nor their own. I believe this was not an act of desperation but an act of asymmetric warfare against us."

The unnamed men, who have been held in Guantanamo for around four years, all left a suicide letter, but the content has not been released.

They had been engaged in a hunger strike to protest their indefinite imprisonment and had been force-fed before quitting their protest, said Harris.

One of the men was an Al Qaida operative, and another had been captured in Afghanistan, while the third belonged to a splinter group.