Some 800 women who had joined Daesh are being detained in the Kurdish regions of northern Syria with their children, German newspaper Die Welt reported on Saturday, citing a terrorism expert from Human Rights Watch (HRW).

Among the 800 were 15 German women, HRW's Nadim Houry said. He told the paper he had met and spoken to the women in January. The female Daesh members and their children were detained across several camps in the region, he said.

The women were from 40 different countries including Canada, France, Britain, Turkey and Australia, Houry said.

"These women are in a very difficult situation," he said. "Especially for the small children the conditions are by no means good."

The women wanted to return home even if that meant having to face prosecution, he added.

Houry called on European governments to allow the children to return.

"The children have not committed any crimes, they are the victims of the war and often their radicalized parents."