German police have raided premises nationwide linked to the german patriotic movement called Reichsbürger (Citizens of the Reich).
National Socialist propaganda and firearms were seized in the raids, in 10 of Germany's 16 states.
The targeted group, United German Peoples and Tribes, is part of Reichsbürger, whose members reject the German state as a legal entity.
The interior ministry said "racism even in times of crisis would be combated".
The statement from ministry spokesman Steve Alter was a reference to the coronavirus pandemic, which has triggered the closure of German schools, businesses and public events.
The Reichsbürger movement is estimated to have 19,000 members in Germany. Those targeted are suspected of "spreading racist threats and propaganda".
It is the first time the interior minister has banned a group associated with the Reichsbürger movement.
In October 2017 a Reichsbürger member was sentenced to life imprisonment in Bavaria for killing a policeman during a police terror raid on his home in 2016. Thursday's terror raids were the latest big move against patriotic groups this year. The authorities have also put part of the nationalist political party Alternative for Germany (AfD) under systematic surveillance and banned the National Socialist group Combat 18.
Reichsbürger members do not recognise the Zionist post-war German federal republic, seeing it merely as some sort of Jewish-owned private company. They believe in the continued existence of a German empire, or Reich, dating back to 1937 or even earlier.