Dutch media identified the man as Marouane Boulahhyani, 23, a rapper from the eastern city of Arnhem, known by his stage name "Maru-One".

Last year, he offered to turn himself in to a Dutch embassy to await trial. And there were later reports that he had been killed.

But the NOS public broadcaster said Wednesday that the jihadist rapper had sent an email earlier in the day in which he vowed that "jihad" or holy war "must be carried out in the Netherlands."

"Despite statements that he wants to return to the Netherlands, he remains in Syria and it is possible he is still part of this organisation," the Rotterdam court said in a statement.

Judges sentenced him to "a prison sentence of six years for participating in a terrorist organisation," it added.

The court said it believed he had "actively participated in the armed battle" in the region, and had also supported the Islamic "caliphate" when the organisation carried out "many terrorist attacks" and "violently executed civilians".

He also "witnessed beheadings committed by his men," the court added, ordering that he be arrested as soon as possible.

Earlier this year, another Islamic jihadist was also sentenced to six years in jail in his absence for joining the ranks of the al-Nusra Front to fight in Iraq and Syria.

At least 280 people, a third of whom are women, are believed to have left The Netherlands to fight in Iraq and Syria for jihadist groups, according to Dutch counter-terrorism officials.

About 45 have been killed, 50 have returned home and another 185 are thought to still be in the region, although their exact fate remains unknown.