Federal prosecutors said today that 20-year-old Hekmat T was arrested a day earlier on suspicion of membership in a terrorist organization.
Prosecutors alleged the man joined the Taliban in Afghanistan in 2013 and repeatedly took part in fighting against Afghan police and security forces.
The statement didn't say where the man was arrested or why he was in Germany. His full name wasn't provided due to German privacy laws.
Thousands of Afghans have come to Germany in recent years seeking asylum due to the conflict in their home country.