A report drawn up by the security services estimates there is a "high double-digit number" of public servants who belong to the "Reichsbuerger," or Citizens of the Reich, a mystical nationalist movement which maintains that the Reich continued after Germany's defeat in World War Two, Spiegel reported.
Investigations are underway against 11 members of Bavaria's state police, five of whom have been suspended from duty. There have also been 11 cases in Germany's Federal Police and four of them have had their service weapons confiscated, Spiegel said.
Up to five cases have been identified in the armed forces.
The German domestic intelligence agency declined to comment on the Spiegel report.
It has previously estimated that the Reichsbuerger have a total national membership of about 16,500 and considers 900 of these to be "far-right extremists."
German authorities are highly sensitive to signs of far-right radicalism in their ranks.
The post-war German Federal Republic was founded as an explicitly liberal project to repudiate the crimes of the Nazis' Third Reich, which committed some of history's worst crimes, including the genocide of six million Jews.
Despite a ban on groups that threaten political violence or seek to overturn Germany's constitutional order, some individuals do fall through the cracks.
Investigations are still underway against a former high-flying army officer who last year was found to have been plotting to carry out violent attacks.
A member of the 'Reichsbuerger" shot dead a police officer in Bavaria in October 2016 as a police team was about to enter his home to seize his hunting and sports guns. Authorities deemed he was not fit to hold them as a member of the group.