The report, issued on Tuesday to correspond with the second anniversary of the start of the Syrian conflict, estimates there are 2 million children affected by the crisis inside Syria.

Another 500,000 children are thought to be among the million refugees in Jordan, Lebanon, Turkey, Iraq and Egypt, which are struggling to cope with the constant stream of refugees.

"Millions of children inside Syria and across the region are witnessing their past and their futures disappear amidst the rubble and destruction of this prolonged conflict," said UNICEF Executive Director Anthony Lake in a statement accompanying the release of the report.  "As their right to be children is denied . . . their views of their neighbors are colored in ways that can create future generations of self-perpetuating violence."

Among the problems facing Syrians are the destruction of basic infrastructure and public services, the report says. Children's education has also been severely affected, as UNICEF reports that one in five schools has either been destroyed or is being used by people seeking shelter.

The report adds that children are being killed, maimed, abused and tortured in the violence that has swept the country. Many are also now orphans.

Lack of funding

While UNICEF highlighted some of the relief work it is carrying out in Syria and in the refugee camps in neighboring countries – such as vaccination drives and efforts to provide safe drinking water – the organization says it is still seriously underfunded to effectively combat the crisis. It says it has only received 22 percent of the $68 million (52 million euros) needed to continue and expand existing programs.

The ongoing violence in Syria makes the country a dangerous place for UNICEF to operate, added Ted Chaiban, Director of UNICEF's Emergency Program, who travelled to Syria last month.

"We have very significant security constraints, and we have had difficulties also negotiating access," he said. "We're really trying our best – across lines, wherever children and women – people in need are, but the resource base has been difficult to mobilize for this crisis."

Meanwhile, fighting between Syrian rebels and government enters its third year on Tuesday. The UN estimates 70,000 people have been killed in the conflict.