Group includes 11 US citizens, including five minors, but tens of thousands of people remained detained five years after defeat of IS

The Kurdish fighters are holding more than 56,000 detainees with alleged or perceived links to the Islamic State group.

According to a recent Amnesty International report, some 29,000 children are held in the two largest camps, representing “the highest concentration of children arbitrarily deprived of their liberty anywhere in the world”.