Nearly half of all children in Afghanistan are out of school due to conflict, poverty, child marriage and discrimination against girls, the number rising for the first time since 2002, humanitarian organizations said Sunday in a report.

Spreading violence has forced many schools to close, undermining fragile gains in education for girls in a country where millions have never set foot in a classroom.

Some 3.7 million children between the ages of seven and 17, or 44 percent, are out of school, 2.7 million of them girls, Education Minister Mirwais Balkhi told a seminar, explaining a study conducted by UNICEF, USAID and the independent Samuel Hall think tank.