German prosecutors say they have formally indicted one of the country's most prominent Islamic extremists on suspicion of supporting a foreign terror group.

Federal prosecutors say Sven Lau is accused of four counts of supporting the group Jaish al-Muhajireen wal-Ansar, or JAMWA, which was designated as a terrorist organization by the U.S. last year.

Prosecutors said Tuesday that the 35-year-old Lau was the go-to contact for extremists wanting to fight for JAMWA in Syria and provided material support to the group. It split in late 2013 and the faction supported by Lau joined the Islamic State group.

Lau, a convert to Islam, made headlines in 2014 when he attempted to establish a "Sharia police" in the city of Wuppertal to enforce a strict interpretation of Islam.