The United Nations Children's Fund (UNICEF) said in a report released late Monday that at least 10,000 children have been killed in the Syrian conflict. However, the organization noted that the actual number was probably much higher.

After three years of civil war, hundreds of thousands of Syrian children remain trapped in besieged parts of the country, said UNICEF.

"Syria is now one of the most dangerous places on earth to be a child," said the report. "In their thousands, children have lost lives and limbs, along with virtually every aspect of their childhood."

"They have lost classrooms and teachers, brothers and sisters, friends, caregivers, homes and stability," it added. "Instead of learning and playing, many people have been forced into the workplace, are being recruited to fight, or subjected to enforced idleness."

UNICEF has singled out the conflict's use of child soldiers by both rebel and military fighters, launching a campaign last week aimed at ending their recruitment by government forces in the country by 2016.

"The dangers for children go beyond death and injury," UNICEF said Monday. "Boys as young as 12 have been recruited to join the fighting, some in actual combat, others to work as informers, guards or arms smugglers."

Twice the number of children affected

A total of 5.5 million children have been affected by the conflict, more than twice the number UNICEF estimated in March 2013. Nearly 3 million young Syrians have been displaced inside the country, up from 920,000 last year. The total number of child refugees has risen from 260,000 a year ago to 1.2 million. Some 425,000 of those refugees are under the age of five.

The report said 2 million children were in need of some form of psychological support or treatment, while noting the war's devastating impact on schooling.

"The decline in Syrian children's access to education has been staggering," UNICEF said. "Today, nearly 3 million children in Syria and in neighboring countries are unable to go to school on a regular basis. That's about half of Syria's school-age population."

The problems extend outside Syria's borders, said the report. One in every five Syrian girls in Jordan is forced into an early marriage, while one in 10 Syrian refugee children is now working.

"This war has to end so that children can return to their homes and rebuild their lives in safety with their family and friends," said UNICEF Director Anthony Lake. "This third devastating year for Syrian children must be the last."

dr/jm (Reuters, dpa)