Story highlights U.N. official says the terror group is using mentally-challenged children

She urges Iraq to protect children nationwide

(CNN) ISIS has stepped up the use of children in its bloody campaign of terror, the United Nations says -- subjecting them to horrors that include putting price tags on them to sell as slaves.

A report released this week focused on children in Iraq, as well as the responsibility of that nation's government for ensuring the safety and security of young civilians in the conflict. But it certainly doesn't preclude similar things happening in Syria, where ISIS is also entrenched and also has been blamed for various atrocities.

In reference to Iraq, at least, the U.N. report found that the terrorist group is resorting more and more to brutal acts such as enslaving, raping, beheading, crucifying and burying people alive. Some of those affected are children.

"We have had reports of children, especially children that are mentally challenged, who have been used as suicide bombers, most probably without them even understanding what has happened or what they have to expect," said Renate Winter, an expert with the U.N. Committee on the Rights of the Child.

Some as young as age 8 are getting training to become soldiers, she said.

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