KABUL - Nearly a third of all children in war-torn Afghanistan are unable to attend school, leaving them at increased risk of child labor, recruitment by armed groups, early marriage and other forms of exploitation, an aid group said on Thursday.

Save the Children said more than 400,000 Afghan children are expected to drop out of school this year due to growing instability and the forcible return of Afghan refugees from Pakistan, adding to the 3.7 million already out of school.

More than 600,000 Afghans returned from Pakistan last year and around 1 million more are expected this year after the tightening of regulations by authorities there.