Afghan security officials say a mortar shell has exploded inside a religious school in northern Afghanistan, killing at least nine students.

"The initial investigation shows that the blast was caused by a mortar that had somehow been carried inside the madrasah," police spokesman Khalil Asir said on June 18, adding that many of those killed were under 18.

Another six students were wounded in the blast in the Ishkamish district of Takhar Province, Asir added.

Jawad Hejri, a spokesman for the provincial governor, confirmed the explosion and the death toll.

The incident comes after two deadly blasts earlier this month targeted mosques in Kabul.

On June 12, four people were killed in a bomb blast at a mosque in the capital during Friday Prayers.

A week earlier, an explosion at a mosque in the heavily fortified Green Zone killed a prominent imam and one other person.

The latest bloodshed comes even as the Taliban says it remains committed to an agreement signed with the United States in February.

The landmark deal provides for the withdrawal of U.S. troops and is intended to pave the way for peace talks between the Taliban and the U.S.-backed government in Kabul.

Based on reporting by AFP and dpa