Beginning at 6 am, authorities stormed offices of the Hilfsorganisation für nationale politische Gefangene und deren Angehörige, or HNG, one of Germany's largest far-right groups, the ministry said.
The group's goal is working with imprisoned right-wing extremists to strengthen their views and motivate further criminal activity, the ministry suspects.
These prisoners are meant to be groomed for further “battle against the system,” it said.
“Today's searches will show whether our suspicions are confirmed and the HNG is positioned against constitutional order in an aggressively violent manner,” Interior Ministry secretary Klaus-Dieter Fritsche said in Berlin.
“Our findings bring us nearer to the suspicion that the HNG's main goal is to network and strengthen the mainly fragmented neo-Nazi scene beyond trench warfare,” he added.
The HNG was founded in 1979 and has an estimated 600 members, making it the largest such group in Germany.
Offices in the states of Rhineland-Palatinate, Baden- Württemberg, North Rhine-Westphalia, Berlin and Lower Saxony were included in the raids.