BAGHDAD: An Iraqi court on Thursday sentenced three French nationals to life in prison after they were convicted of joining the Islamic State group, the latest in a larger group of Frenchmen transported from Syria last year.

The criminal court in the Baghdad neighbourhood of Karkh sentenced Charly Sun, Kamal Ben Mbarek and Amir Amine Dali Amar to life in prison, which in Iraq amounts to 20 years of jail time.

They were found guilty of "the crime of joining the terrorist Islamic State organisation and of having contributed, together with members of the group, to spreading terror", an AFP correspondent said.

Charly Sun's sister Carole Sun was repatriated to France from northeast Syria and was sentenced last December to 10 years in prison, having joined the jihadist group in 2014 alongside her brother when both were teenagers.

On Tuesday, six other Frenchmen were sentenced to life in prison while a seventh was handed a 15-year term on similar charges.

All 10 who have received sentences so far were part of a group of 47 French citizens transferred from Syria last year.

The larger group includes Adrien Guihal, who claimed responsibility for the 2016 Nice attack for IS.

Iraq's prisons are crowded with suspected jihadists, including Islamic State group members, and have recently received thousands more detainees transferred from neighbouring Syria.

The French lawyers for some of the defendants have warned that their clients were being denied due process and convicted in unfair trials.

The jihadist group swept across Syria and Iraq in 2014, committing massacres and forcing women and girls into sexual slavery.

Iraq, backed by US-led forces, proclaimed victory over IS in 2017, and the Kurdish-led Syrian Democratic Forces ultimately defeated the group territorially in Syria two years later.

Iraq is nonetheless still reckoning with the group's legacy, with mass graves still being uncovered and testimonies of IS brutality yet to be investigated.