German supermarket giant Rewe sold extremist propaganda in at least one of its stores, Funke media group papers reported on Saturday (German language).

Magazin2000plus was available from the shelves of a Berlin branch, but Rewe could not verify how widely the magazine was distributed throughout its nationwide chain of stores.

The magazine ran several articles that carried the messages of the Reichsbürger movement, a banned far-right organization with similarities to the US "sovereign citizen" movement.

Read more: Federal Criminal Police call Reichsbürger a terror threat

The group has been designated a terrorist group and is considered to be far-right, nationalist, and often anti-Semitic.

Its proponents tout the conspiracy theory that the Federal Republic of Germany does not legally exist because Germany never signed a peace treaty with the Allies at the end of World War II. According to their conclusively debunked line of thinking, Germany is an occupied country and its borders remain unchanged from the German Reich - either of 1871 or 1937.

Its followers do not recognize the authority of the German government or its constitution, or Basic Law, and often refuse to pay tax.

Police have seized large weapons caches belonging to followers the ideology

Increasingly violent

The group has 12,600 followers throughout Germany, according to the German domestic intelligence agency - including members in the police force.

Read more: A guide to Germany's far-right groups

Reichsbürger followers often print their own passports and driver's licenses for their make-believe states, ignoring the fact that such activity is illegal. Their websites carry messages that they intend to "carry on the fight against the Federal Republic of Germany."

The group has gained notoriety in recent years for its increasingly violent nature. Police have seized large caches of weapons and ammunition, while one follower has been charged with killing a policeman. In Höxter, North Rhine-Westphalia a group from the "Free State of Prussia" even attempted to build up its own militia by smuggling in arms from outside the country.

Read more: German far-right 'Reichsbürger' police murder trial begins

Magazine promotes ideology

The magazine that Rewe was reportedly selling was addressed to "everyone who carries a personal ID," referring to the government issued identification cards Germans are required to hold.

Its articles reportedly argued that Germany is a limited liability company and Chancellor Angela Merkel is the managing director, a common chain of argument used by Reichsbürger followers.

Another article reportedly argued that the Basic Law, or constitution, adopted after World War II, was used as a "means of occupation by the Allies" and was only provisional. Therefore, it argued, the German Reich continues to exist under international law, and the Federal Republic has no constitutional basis.

Right to display

Rewe told Berliner Morgenpost that its selection of magazines is decided by the press wholesaler that supplies them. Furthermore, "all magazines have a right to appearance and display, so long as the content does not violate relevant laws," a spokesman said.

"Right-wing and left-wing extremist publications also fall within the scope of freedom of expression and freedom of the press," he was quoted as saying.

The magazine claims a print-run of 30,000. It tends to publish esoteric articles, often dealing with UFOs, conspiracies, free energy and alternative medicine. The publisher Ingrid Schlotterbeck has described herself in interviews as the "Foreign Minister" of the "Commissary Government of the German Reich."