The U.S. military on Thursday released three teenage boys -- believed to be between the ages of 13 and 15 -- who had been accused of supporting the Taliban (search) and had been held at the prison for terror suspects at Guantanamo Bay, Cuba, the Pentagon announced.

The boys were sent back to their home country --which was not identified, the Pentagon said, saying it was determined that they no longer posed a threat to the United States. They have no further value as interrogation subjects and are not going to be tried by the U.S. government for any crimes, the military said.

They were the youngest prisoners at the Guantanamo base (search), which has held hundreds of suspected Al Qaeda (search) and Taliban fighters since the U.S.-led war in Afghanistan that followed the Sept. 11, 2001, attacks.

The boys' identities were not released. In a statement, the Pentagon said their identities were being kept secret for fear of reprisals against them. The three came from the same country, but the Pentagon would not identify what that country was.

Two of the boys were captured during U.S. and allied raids on Taliban camps in Afghanistan; the third was captured trying to obtain weapons for the Taliban, the Pentagon said. All three had arrived at the Guantanamo prison in February 2003, a spokeswoman at the prison said.

Human rights groups had campaigned for their release for some time, saying the long separation from their families was hurting the boys. In August, the general running Guantanamo agreed they should be sent home but said he was awaiting orders from the Pentagon and other U.S. government agencies.

Vienna Colucci, an international justice specialist with Amnesty International, welcomed the boys' release but said the U.S. government violated international norms by keeping them.

"It certainly should not have gone on this long," she said of their detention. "It's not at all in compliance with the basic principles that guide the treatment of juveniles."

Those principles include access to their parents and attorneys, she said.

Aid groups will help resettle them in their home country, the Pentagon said.

In November, officials at the base said the three were kept apart from the other prisoners, including older boys aged 16 and 17. They were given some freedom of movement within their section of the prison, and guards said they liked to kick soccer balls.

The Pentagon believes the boys are between the ages of 13 and 15 but their actual birthdays are not known. The Pentagon said medical tests had determined all three were under age 16.

Their release means that 87 detainees have been released from the prison. Another four have been transferred to Saudi Arabia for detention there.

About 650 prisoners remain at Guantanamo, military officials said Thursday.

During their captivity at Guantanamo, the boys wore orange jumpsuits and frequently met with psychiatrists. They were taught math, reading and writing in their native language, and picked up some English, guards said.

The teenagers had a refrigerator stocked with apples, oranges, pears and dates. When they cooperated, they got snacks and extra movie time. When they didn't, they were confined to their rooms.

They exchanged censored mail with relatives through the International Committee of the Red Cross, the only independent group allowed access to the detainees.