Some 15 premises in the states of Bavaria, Baden-Wuerttemberg and Rhineland-Palatinate are being searched, police said.
Some of the searches are being conducted with tactical response units present due to the possibility that the suspects might act violently, Upper Bavaria police said.
Seven people are suspected of engaging in forgery by producing documents purportedly issued by the "German Reich".
Nine others are suspected sympathisers or customers.
German authorities have expressed growing concern about the grouping, which has been compared to the US sovereign citizen movement.
A police officer was killed and three others were wounded last year in armed stand-offs with members of the so-called Reich Citizens' Movement.