BERLIN (Reuters) - German police have arrested a 22-year-old German national who they suspect was returning from Syria after fighting for the militant group Islamic State in the country’s civil war, Germany’s federal prosecutor’s office said on Friday.

The man, named only as Tarik Suleymann S. due to German privacy laws, travelled to Syria in November 2013 and joined IS by January 2014 before being arrested at Frankfurt airport on Wednesday, the prosecutor’s office said in a statement.

He was trained to use guns and took part in fighting, the prosecutor’s office said, adding that he had promoted the extremist group in online postings and videos and called for violence against “infidels” in Germany.

Tarik Suleymann S. was presented to a judge on Thursday and remanded in custody.

Germany considers IS to be a terrorist organisation and membership of such groups is punishable under German law.

In January, criminal police said the number of Islamist militant fighters returning to Germany from Syria and Iraq was on the rise and that more than 400 people were being watched for posing a threat.