A US-backed Kurdish force in northeast Syria handed over 100 alleged ISIS fighters to Baghdad this week, a senior Iraqi security source told AFP on Sunday.
The Iraqi fighters were being interrogated before being transferred to the judiciary, the source said.
But an official with the Syrian Democratic Forces (SDF) denied the handover had taken place.
The semi-autonomous Kurdish administration is sometimes reluctant to discuss issues related to ISIS fighters or their families held in SDF prisons and camps.
The Kurdish force has already handed over around 900 Iraqis caught fleeing the last remnants of the extremist “caliphate” in 2019.
Around 1,600 Iraqis were still detained in northeast Syria at the end of last year over allegedly fighting for ISIS, according to a United Nations report released this month.
Iraq has tried thousands of its nationals for belonging to a “terrorist” group, which carries the death penalty according to the country’s 2005 Counter-Terror Law.
Hundreds of them have been condemned to death but only a small portion of the sentences have been carried out as they require presidential approval.
Current President Barham Saleh is known to be against capital punishment.
Two senior officials from the US-led coalition told AFP that the original deal was also meant to include the transfer of at least 500 Iraqi civilians from the Al-Hol displacement camp in northeast Syria to Iraqi territory.
Al-Hol is home to over 60,000 people who fled IS territory as the SDF closed in on the extremists.
About half of those living in the camp are Iraqis.
Kurdish authorities have insisted they must return to their homeland but the government in Baghdad has been slow to act.