The U.S. military is holding about 500 juveniles suspected of being "unlawful enemy combatants" in detention centers in Iraq and has about 10 detained at the U.S. base at Bagram, Afghanistan, the United States has told the United Nations.

A total of 2,500 youths under the age of 18 have been detained, almost all in Iraq, for periods up to a year or more in President George W. Bush's anti-terrorism campaign since 2002, the United States reported last week to the U.N.'s Committee on the Rights of the Child.

Civil liberties groups such as the International Justice Network and the American Civil Liberties Union (ACLU) denounced the detentions as abhorrent, and a violation of U.S. treaty obligations.

In the periodic report to the United Nations on U.S. compliance with the Convention on the Rights of the Child, the United States confirmed that "As of April 2008, the United States held about 500 juveniles in Iraq."

"The juveniles that the United States has detained have been captured engaging in anti-coalition activity, such as planting Improvised Explosive Devices, operating as lookouts for insurgents, or actively engaged in fighting against U.S. and Coalition forces," the U.S. report said.

The majority are believed to be 16 or 17 years old. In the United States a 17-year-old can enlist in the U.S. army, with parental consent.

The report said that of the total of 2,500 juveniles jailed since 2002, all but 100 had been picked up in Iraq. The vast majority of the remainder were swept up in Afghanistan.

A total of eight juveniles have been held at the Guantanamo Bay detention facility, but all were released from 2004 to 2006.

"It remains uncertain the exact age of these individuals, as most of them did not know their date of birth or even the year they were born," the report says. But U.S. military doctors who evaluated them believed that three were under age 16.

In Afghanistan, "As of April 2008, there are approximately 10 juveniles being held at the Bagram Theater Internment Facility as unlawful enemy combatants," the reports said.

In Bagram, a U.S. military spokesman, Marine 1st Lt. Richard K. Ulsh, told the AP: "At any time there are up to 625 detainees being held at the Bagram Theater Internment Facility. There are no detainees being held under the age of 16 and, without getting into specifics due to the frequent fluctuation in the number of detainees being held, we can tell you that there are currently less than 10 detainees being held under the age of 18."

Civil liberties groups were outraged.

"It's shocking to me that the U.S. government has not figured out a way to keep children out of adult prisons. It's outrageous, and it is not making us any safer, I can say that about Afghanistan from personal experience," Tina M. Foster, the executive director of the International Justice Network, told the AP on Sunday. Her group brought lawsuits on behalf of the Guantanamo detainees in 2006, and has taken on the cases of adult detainees in Bagram.

"If people were caught on the battlefield planting bombs, that's information that the U.S. government should have produced in some procedure," Foster said. She said the U.S. military does not release the names of juveniles it is holding in Bagram, so her group is trying to learn who they are by finding Afghan relatives.

"It is shocking to know that the U.S. is holding hundreds of juveniles in Iraq and Afghanistan, and even more disturbing that there is no comprehensive policy in place that will protect their rights as children," Jamil Dakwar, director of the American Civil Liberties Union's Human Rights Program, said in a statement. "Juveniles and former child soldiers should be treated first and foremost as candidates for rehabilitation and reintegration into society, not subjected to further victimization."

According to the ACLU, the lack of protections and consideration for the juvenile status of detainees violates the obligations of the U.S. under the Optional Protocol on the Involvement of Children in Armed Conflict that the U.S. ratified in 2002, as well as universally accepted international norms.

The U.N. Committee on the Rights of the Child is scheduled to question the U.S. government delegation on its compliance with its obligations on May 22 in Geneva.

The U.N. Convention on the Rights of the Child was adopted by the General Assembly in 1989, with backing at the time from the U.S. government of President Bill Clinton, and with strong lobbying from then-first lady Hillary Rodham Clinton, who now is competing for the Democratic Party presidential nomination with Barack Obama.