A German man has been convicted of joining the Islamic State group in Syria and fighting for the extremist organization.

The Duesseldorf state court said Thursday that 22-year-old Nezet Alija S., whose full name wasn't given in accordance with privacy laws, was convicted of membership in a foreign terror organization and sentenced to two and a half years in prison.

The court says he spent three months in Syria in 2014 undergoing military training with the group, and took part in combat at least once.

They say there was no evidence he was planning an attack inside Germany.

The dpa news agency reported the suspect told the court that his decision to join IS was "total idiocy" and that he was "happy to be back here" in Germany.