KABUL, Afghanistan — Children have been increasingly bearing the brunt of the war in Afghanistan, a new United Nations report says. The report details an array of hazards, including recruitment of child bombers, school attacks and sexual abuse of minors in government custody.

The number of children killed or injured in the Afghan conflict last year climbed to 1,756 — representing an average of 4.8 child casualties a day and marking a substantial increase over the 1,396 children hurt or killed in the previous year, according to a global report on children and armed conflict.

The U.N. children’s agency, UNICEF, on Wednesday expressed “deep concern” about trends in Afghanistan highlighted in the report, which was released earlier this week in New York by Secretary-General Ban Ki-moon.

“The death or maiming of a single child is a tragedy,” said UNICEF’s deputy Afghanistan representative, Vidhya Ganesh. “It is imperative that all parties to the conflict do everything they can, right away, to protect the lives and basic rights of the children of Afghanistan.”

Separately, the United Nations has documented a drop of more than 20 percent in overall civilian casualties in Afghanistan in the first four months of the year, but said some of that decrease was probably due to seasonal factors. The country was gripped this year by a particularly harsh winter, which dampened the overall level of violence during the cold months.

The parts of the global-conflict report dealing with Afghanistan highlighted the disturbing practice of children being recruited as suicide bombers or unwittingly carrying explosives that are detonated by remote control. The report cited at least 11 such cases last year in Afghanistan.

The Taliban movement is responsible for use of the bulk of child combatants, but UNICEF called on all armed groups in Afghanistan, including the Afghan military, to refrain from recruiting minors.

