Officials previously denied one incident mentioned in news article and had not reported other incidents, which the military called "self-injurious behavior" aimed at getting attention rather than serious suicide attempts.
The coordinated attempts were among 350 "self-harm" incidents that year, including 120 so-called "hanging gestures," at the secretive prison that opened after the Sept. 11 attacks, according to Lt. Col. Leon Sumpter, a spokesman for the detention mission.
In the Aug. 18-26, 2003, protest, nearly two dozen prisoners tried to hang or strangle themselves with clothing and other items in their cells, demonstrating "self-injurious behavior," the U.S. Southern Command in Miami said in a statement. Ten detainees made a mass attempt on Aug. 22 alone.
Last year, there were 110 self-harm incidents, Sumpter said.
The 23 prisoners were in steel mesh cells and they can talk to neighbors. It would not have been possible to pass notes, and they are allowed to exercise only one at a time.
Only two of the 23 were considered suicide attempts — requiring hospitalization and psychiatric treatment. Officials said they differentiated between a suicide attempt in which a detainee could have died without intervention, and a "gesture" aimed at getting attention.
Sixteen of the 23 remain at Guantanamo; seven have been transferred to other countries.
The military has reported 34 suicide attempts since the camp opened in January 2002, including one prisoner who went into a coma and sustained memory loss from brain damage.
The 2003 protests came as the camp suffered a rash of suicide attempts after Maj. Gen. Geoffrey Miller took command with a mandate to get more information from prisoners accused of links to al Qaeda or Afghanistan's ousted Taliban regime, which had sheltered Osama bin Laden.
Critics linked the two and criticized the delay in reporting the incidents.
"When you have suicide attempts or so-called self-harm incidents, it shows the type of impact indefinite detention can have, but it also points to the extreme measures the Pentagon is taking to cover up things that have happened in Guantanamo," said Alistair Hodgett, a spokesman for Amnesty International in Washington, D.C.
"What we've seen is that it wasn't simply a rotation of forces (guards) but an attempt to toughen up the interrogation techniques and processes," he added.
Dr. Daryl Matthews, a forensic psychiatrist at the University of Hawaii, said he believed he was misled during a visit to Guantanamo in June 2003 to investigate and make recommendations about detainees' mental health care, at the request of the Army surgeon general.
"There were many things I wanted to see that I was precluded from seeing, particularly with the interrogation issues," Matthews told The Associated Press in a telephone interview. "In no way did I get honest or accurate information. I feel like I was being systematically misled."
He criticized some practices, and said it was "appalling" that medical professionals shared detainees' medical records with interrogators.
Some 558 prisoners are at Guantanamo Bay, many held for more than three years without charge or access to attorneys.
The latest report comes against a backdrop of recently revealed abuse allegations and mistreatment at Guantanamo Bay, much of which allegedly occurred under Miller.
In a letter obtained by AP, a senior Justice Department official suggested the Pentagon didn't act on FBI complaints about four incidents at Guantanamo: a female interrogator grabbing a detainee's genitals and bending back his thumbs; a prisoner who was gagged with duct tape; and two incidents involving the same man — a dog being used to intimidate him and later putting the man in isolation until he showed signs of "extreme psychological trauma."
One Marine told an FBI observer that some interrogations led to prisoners "curling into a fetal position on the floor and crying in pain," according to the letter dated July 14, 2004.
"The question that needs to be asked is what was the connection between the events and the interrogation techniques or circumstances of detention," said Leonard Rubenstein, director of Physicians for Human Rights in Cambridge, Mass.
Army Gen. Jay Hood, who succeeded Miller last year, has said the number of incidents has decreased since 2003, when the military set up a psychiatric ward.
Lt. Col. Pamela Hart, who was a spokeswoman for the detention mission in August of 2003 said she knew nothing of the mass protest. She is now a Pentagon spokeswoman for the Army.
Southern Command said the detainees' mood and ability to communicate with one another was constantly being assessed at Guantanamo. The assessment, the command said in a statement, "has enabled the leadership to take numerous measures to reduce the opportunity for detainees to communicate a coordinated self-harm incident, or strike out at another detainee or the guard force."
The mass protest was mentioned casually during a visit to Guantanamo in January by three journalists, but officials denied there had been a mass suicide attempt.
By Paisley Dodds