ISIS Committing 'Murderous' Atrocities on Iraqi Civilians, UN Says

— -- As Iraqi and Kurdish fighters move in on the city of Mosul, the United Nations says it is receiving reports of the "murderous" atrocities committed by ISIS, including extrajudicial killings and summary executions against women, children and male civilians in Iraq.

The UN also said it continues to receive information that ISIS fighters are "deliberately" using civilians as human shields -- "forcing them to move to sites where ISIL fighters are based, or preventing them from leaving other places for strategic reasons."

On Saturday, ISIS fighters reportedly shot and killed three women and three girls from a village called Rufeila in the al-Qayyarah sub-district, south of Mosul. The victims were allegedly shot because they were trailing about 100 meters behind other villagers who were being forced by ISIS to relocate to another sub-district, according to the UN.

The victims, which also included four children who were injured, were lagging behind because one of the children had a disability. She was apparently among the victims who were killed.

Human rights staff in Iraq have been informed that ISIS killed 15 civilians in the Iraqi village of Safina, about 28 miles south of Mosul. The dead bodies were thrown in a river in an apparent attempt to spread terror among other residents, according to the UN. On Oct. 19, ISIS allegedly tied six civilians to a vehicle by their hands and dragged them around the village, "simply because they were related to a particular tribal leader fighting" alongside Iraqi forces.

The next day, Iraqi security forces reportedly found bodies of 70 civilians ridden with bullet holes inside houses in the Tuloul Naser Village, located about 22 miles south of Mosul. It is unclear at this point who was responsible for those killings, the UN announced.

"We very much fear that these will not be the last such reports we receive of such barbaric acts" by the terrorist group, the UN said, calling on government forces and their allies to "ensure their fighters do not take revenge on any of the civilians who escape from areas" under ISIS control and treat all suspected ISIS fighters they capture in accordance with international humanitarian law.

The UN also said it is "concerned" by "severe" measures taken by officials in the Iraqi city of Kirkuk on residents now displaced after a surprise attack from ISIS on Friday. The only option given to those who wish to stay in the city is to move into established camps, which are either "already full or very close to full," the UN said.

It could take advancing troops more than two months to liberate Mosul from ISIS control, a Kurdish military commander told ABC News last week.

"We understand that hundreds of families have now been evicted by Kurdish Security Forces, and are worried that if the evictions continue, it could significantly complicate the already alarming situation of mass displacement in the region," the UN said.