SAN JUAN, Puerto Rico - The U.S. military said 23 Guantanamo Bay terror suspects carried out a coordinated effort to hang or strangle themselves in 2003 during a week-long protest in the secretive camp in Cuba.

The military, which had not previously reported the protest, called the actions "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," Lt. Col. Leon Sumpter, a spokesman for the detention mission, said Monday.

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 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-Qaida or Afghanistan's ousted Taliban regime, which had sheltered Osama bin Laden.

"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.

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.

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.