The U.N. human rights chief has urged Turkey to allow investigators to probe allegations of violations committed by Turkish security forces.

Zeid Raad al-Hussein said he has received reports of unarmed civilians being deliberately shot by snipers or from military vehicles in the course of security operations in southeastern Turkey. Those operations focused on mainly Kurdish towns where militants and youths linked to the outlawed Kurdistan Workers' Party are active.

"While Turkey has a duty to protect its population from acts of violence, it is essential that the authorities respect human rights at all times while undertaking security or counter-terrorism operations," he said.

The U.N. wants to investigate reports more than 100 people were burned to death in the town of Cizre while sheltering in basements surrounded by security forces.