They were handed over to Iraqi authorities by the US-backed Syrian Democratic Forces, which ousted IS from swathes of eastern Syria including territory bordering Iraq.

"We received the interrogation files of nearly 900 Iraqi Daesh (IS) members coming from Syria," the court official said, speaking anonymously because he was not authorised to talk to the media.

"The specialised terrorism court has begun setting dates for their trial in batches," the source added.

The nearly 900 suspected jihadists were transferred by the SDF to Iraqi custody in recent months as the remnants of IS' once sprawling self-declared "caliphate" collapsed in neighbouring Syria.

Additional Iraqi suspects are in SDF custody and awaiting transferral, a security source told AFP Sunday.

"They will be handed over in batches on the Syrian-Iraqi border. They include very influential leaders, but IS had sought to keep them hidden," the security source said.

One of those destined to be handed over was deeply involved in IS' efforts to develop chemical weapons, he said.

Iraq has already tried thousands of its own nationals arrested on home soil for joining IS -- including women -- and has sentenced hundreds to death.

The country remains in the top five "executioner" nations in the world, according to an Amnesty International report released last week.

The number of death sentences issued by Iraqi courts more than quadrupled from 65 in 2017 to at least 271 in 2018.

But fewer were actually carried out, according to Amnesty, with 52 executions in 2018 compared to 125 in 2017.

In addition to locals, Iraq has also tried hundreds of foreigners, condemning many to life in prison and others to death, although no foreign IS members have yet been executed.

Among those awaiting trial in Baghdad are 12 accused French IS members, who were caught in Syria and transferred to Iraqi custody in February.

Baghdad has offered to try all foreign fighters in SDF custody -- estimated at around 1,000 -- in exchange for millions of dollars, Iraqi government sources have told AFP.

Rights groups including Human Rights Watch have criticised these trials, which they say often rely on circumstantial evidence or confessions obtained under torture.