GENEVA, May 4 (Xinhua) -- Over four years of conflict in eastern Ukraine has devastated the education system, destroying or damaging hundreds of schools and forcing 200,000 girls and boys to learn in militarized environments, the UN children's fund (UNICEF) said Friday.

"Children are learning in schools with bullet holes in the walls and sandbags in the windows, bomb shelters in the basements, and shrapnel in schoolyards," UNICEF Ukraine representative Giovanna Barberis said at a UN briefing here.

"The education system in eastern Ukraine has been in the crossfire for more than four years. All sides of the conflict must respect international humanitarian law and ensure that schools are safe places for children to learn."

Their education takes place amid volatile fighting and they face dangers due to unexploded weapons of war, and the proximity of military sites, such as bases, storage facilities and security checkpoints, said Barberis.

UNICEF said with its partners it has monitored at least eight instances where military and armed groups' sites are within 500 meters from a kindergarten or school, and two separate locations where schools and these sites are only a few meters apart.

Since the beginning of the current school year, UNICEF has monitored six former school buildings that have been occupied or used by military or armed groups.

At least 45 schools have been damaged or destroyed over the last 16 months. This is in addition to more than 700 schools damaged since the conflict began.

Principal Elena Mihatskaya's Secondary School Number 2, in the town of Krasnohorivka, has been shut down since last May after it was hit by a shell that caused massive damage to the roof and multiple classrooms.

"The children are extremely nervous of shelling and teachers try to calm them down, but it's hard for them," UNICEF quoted her saying in a statement.

This year, UNICEF said it has appealed for 23.6 million U.S. dollars to provide urgent humanitarian assistance to children and families affected by the conflict in eastern Ukraine.

To date, less than 15 percent of this appeal has been met.