German authorities say they have arrested a 31-year-old man at Munich airport on suspicion he had been returning to the country after joining the Islamic State terrorist group in Syria.

Federal prosecutors said Ali R., identified only as a German citizen from the Berlin area, was arrested Friday on charges of membership in a foreign terrorist organization. They didn't give his full name in line with German privacy rules.

He's accused of traveling to Syria in December 2014 to fight for the Islamic State. He allegedly served in an administrative capacity until May 2015, dealing with the arrival of new recruits.

He also is alleged to have helped produce booby traps and was part of an armed escort guarding a supply convoy in August 2015.