United Nations, Aug 23 : UN Children's Fund (UNICEF) Executive Director Catherine Russell has voiced concern over child casualties in the Ukraine conflict. At least 972 children in Ukraine have been killed or injured by violence since the conflict escalated nearly six months ago, an average of over five children killed or injured each day. And these are just the figures the United Nations has been able to verify. It is believed that the true number to be much higher, said Russell in a statement on Monday. She said that most of the child casualties were caused by the use of explosive weapons, which do not discriminate between civilian and combatant, especially when used in populated areas, Xinhua news agency reported. The start of the school year in just over a week's time is a stark reminder of how much children in Ukraine have lost. Ukraine's education system has been devastated by the escalation of hostilities across the country. Schools have been targeted or used by parties, resulting in families not feeling safe to send their children to school. UNICEF estimates that one in 10 schools have been damaged or destroyed, she said. "UNICEF continues to call for an immediate cease-fire in Ukraine and for all children to be protected from harm. This includes ending the brutal use of explosive weapons in populated areas and attacks on civilian facilities and infrastructure. Ukraine's children urgently need safety, stability, access to safe learning, child protection services, and psychosocial support. But more than anything, Ukraine's children need peace," Russell added. /IANS