Four German police officers in Bayern face disciplinary proceedings and possible expulsion for suspected links to the far-right "Reichsbürger" movement, the Bavarian interior ministry said on Thursday.

Speaking to the German broadcaster Bayerischer Rundfunk, Bavaria's interior minister Joachim Herrmann confirmed that one police commissioner had been suspended earlier this year, while investigations into the other three officer's are ongoing.

Herrmann said that the suspended officer had "clearly exposed himself as a Reichsbürger" and had taken part in group meetings.

All four risk being expelled from the police force.

Herrmann said that "if there was any doubt regarding the officer's adherence to the constitution of Bavaria and the German Federal Republic, they should be immediately dismissed."

Bavarian policeman dies after battle with far-right gunman

On Wednesday, a 32-year-old police officer was killed and three others were injured during a shootout with a member of the far-right group in the Bavarian town of Georgensgmünd.

The Reichsbürger movement - which translates as "Citizens of the Reich" - is a far-right movement that refuses to recognize the existence of the current Federal Republic of Germany, maintaining that the German empire continues to exist as it stood before World War II.

Herrmann said that Bavaria's domestic intelligence agency had placed a number of suspected members under surveillance for an extended period of time, which allowed the police to identify members among its ranks.

However, he admitted that state authorities had underestimated the group's propensity for extreme violence.

Nevertheless, Hermann maintained that the police forces had reckoned with the man posing a severe threat. He said an investigation into the shooting and how the officer was killed will take place.

Herrmann also called for an investigation to assert whether other state officials have ties to the Reichsbürger movement. The Bavarian state "needs to have a complete overview of the number of members so that it doesn not underestimate the capacity of the movement," he said.

dm/jr (AFP, dpa)