Tarik Jadaoun -- known by his nom de guerre Abu Hamza al-Beljiki -- pleaded "not guilty" to charges including carrying out attacks on Iraqi troops that could see him handed the death penalty.

Born in 1988, Jadaoun -- who was captured in ex-IS bastion Mosul in August -- appeared before the Baghdad court dressed in a beige prison uniform with a shaved head and bushy moustache.

"I was not a fighter, I was in charge of a group of IS nurses. I took care of everybody," he told the court. "I got lost and I appeal to your kindness."

Jadaoun, who has Moroccan roots, said he was forced by "one of the top IS commanders" to appear in videos threatening attacks against Belgium and France.

The footage saw Jadaoun earn the moniker "the new Abaaoud", after his compatriot Abdelhamid Abaaoud, one of the organisers of November 2015 attacks in Paris.

Earlier, investigators alleged Jadaoun was in charge of the "cubs of the caliphate" -- about 60 children aged eight to 13 who received intensive fitness and weapons training.

There was no mention of those accusations at the court session on Thursday.

The judge postponed the next hearing until May 22, with a judicial source putting the delay down to a lack of diplomatic representation for the accused.

Belgium does not have an embassy in Iraq, but the source said the foreign ministry in Baghdad had sent a letter to representatives from the country.

In total, Iraqi courts have sentenced to death more than 300 people, including dozens of foreigners, for belonging to IS, judicial sources said last month.

Since January, some 100 foreign nationals have been sentenced to death in Baghdad and around 185 to life in prison, officials said.

Thousands of foreign fighters from across the world flocked to the black banner of the jihadists as the group seized swathes of Iraq and Syria in 2014.

Their self-declared "caliphate" has since been reduced to a rump territory of desert in the east of war-torn Syria.

The fate of those who survived ferocious onslaughts by various forces against IS has been a major headache for their home governments, which are often against seeing them return.