Fighters from the al-Qaida linked Islamic State of Iraq and the Levant (ISIL) during a parade in Raqqa, Syria.

Fighters from the al-Qaida linked Islamic State of Iraq and the Levant (ISIL) during a parade in Raqqa, Syria.

A 20-year-old man who once played for Jewish football club Maccabi Frankfurt has gone on trial in Germany, charged with being a member of the extremist Islamic State.

Prosecutors allege that Kreshnik Berisha, travelled to Syria last year and fought with the group before returning to Germany five months later.

Berisha, who could face up to 10 years in prison for membership of a foreign terrorist organisation, was arrested at Frankfurt airport in December and has been detained ever since.

As recently as 2011 he appeared “very nice, unassuming,” according to the chairman of TuS Makkabi Frankfurt, Germany’s most prominent Jewish football club, whose under-17 youth team Berisha played for.

Heightened security measures are in place for the trial, which is expected to last until at least November.

It opens just days after Germany formally banned Islamic State symbols and any propaganda activity for the group.

Authorities say more than 400 people from Germany have joined jihadist groups fighting in Syria since the start of the conflict there. Some are converts to Islam, but many come from Muslim families that have settled in Germany.

Berisha’s alleged radicalisation apparently occurred over the course of a few years.