"Since 2004, an increasing number of children have been recruited into various militias and insurgent groups, including as suicide bombers," Radhika Coomaraswamy told a news conference in the Jordanian capital.

"It is an intolerable situation," said Coomaraswamy, special representative of the secretary general for children and armed conflict.

Winding up a week-long visit to Iraq, she said children there are the silent victims of the ongoing violence in the country, with approximately 1,500 "known to be held in detention facilities."

"Many of them no longer go to school, many are recruited for violent activities or detained in custody, they lack access to the most basic services and manifest a wide range of psychological symptoms from the violence in their everyday lives"

She said only 50 percent of primary school children are attending school, down from 80 percent in 2005. Only 40 percent have access to clean drinking water and there is a continuing possibility of outbreaks of cholera.

She called on religious, political, military and community leaders to send one clear message to Iraqi children: "Stay out of violence and go back to school."

Coomaraswamy strongly urged all parties to the conflict in Iraq "to strictly adhere to international humanitarian standards for the protection of children and to immediately release any children under the age of 18 years who are associated with their forces in any way".