The detainees are among around 7,000 suspects the US military began transferring last month after Syrian government forces captured Kurdish-held territory where they had been held by Kurdish fighters.

They include Syrians, Iraqis and Europeans, among other nationalities.

Saad Maan, a spokesperson for the Iraqi government's security information unit, told AFP that 4,583 detainees had been brought to Iraq so far.

In 2014, IS swept across swathes of Syria and Iraq, committing massacres and forcing women and girls into sexual slavery.

Backed by US-led forces, Iraq proclaimed the defeat of IS in 2017, while in neighbouring Syria the Kurdish-led Syrian Democratic Forces ultimately beat back the group two years later.

The SDF went on to jail thousands of suspected jihadists and detain tens of thousands of their relatives in camps.

In Iraq, where many prisons are packed with IS suspects, courts have handed down hundreds of death sentences and life terms to those convicted of terrorism offences, including many foreign fighters.

This month Iraq's judiciary said it had begun investigations into detainees transferred from Syria.