Police have raided more than 30 premises linked to suspected far-right extremists in Berlin and three other eastern German states.
German news agency dpa reported that the raids were mainly centred on Brandenburg state and the region around Cottbus, about 62 miles south-east of the capital.
According to Brandenburg police, the investigation focuses on about 20 people with ties to Germany's hooligan, martial arts and right-wing extremist scene.
Cottbus has a comparatively large neo-Nazi scene affiliated to the city's main football team, Energie Cottbus.
The raids come a day after authorities in Austria searched dozens of homes in several states, seizing weapons and large amounts of banned propaganda material.
There were no immediate reports of arrests in either set of raids.