German police have detained two people after a series of raids against far-right suspects accused of plotting attacks on refugees, Jews and police officers.

Several of those targeted were considered close to the so-called Reichsbürger (Citizens of the Reich) movement, a shadowy extremist group whose members reject the legitimacy of the German republic.

The chief suspect is a 62-year-old self-proclaimed Celtic druid, who had called for violence against Muslims and Jews in online posts, the DPA news agency and other media reported.

Police swooped on 12 homes and other sites in six states, including Berlin, as part of a federal investigation based on suspicions individuals formed a rightwing extremist organisation, the prosecutor’s office said.

The officers confiscated a variety of weapons including explosives, a spokeswoman said.

Six suspects, believed to be connected primarily via social media, were accused of founding the group “and, in early 2016, beginning plans for armed attacks against police officers as representatives of the state, asylum seekers and members of the Jewish community”.

Another suspect was believed to have offered assistance to the group, including by acquiring weapons.

“The aim of the raids is to gather evidence of the formation of a group as well as suspected crimes and potential material for use in those crimes,” the prosecutor’s office said. “There is not as yet any evidence of specific attack plans.”

Approximately 200 officers took part in the coordinated raids.

The DPA said the group included members of the Reichsbürger movement, which is blamed for shooting dead one police officer and wounding three others during a raid in the southern town of Georgensgmünd in October.

In another attack last August, a member of the group – a former Mr Germany pageant winner – opened fire on officers carrying out an eviction order at his house in the eastern state of Saxony-Anhalt.

The 41-year-old gunman was seriously wounded and three police officers sustained light injuries.

Most Reichsbürger members believe in the continued existence of the German empire (Reich) and many refuse to pay taxes, social security contributions and fines owed to the state.

The group is thought to overlap with neo-Nazis, adherents of conspiracy theories and other esoteric beliefs.

According to the domestic intelligence service, the Reichsbürger movement has about 10,000 members.

“The Reichsbürger group … continues to win new followers,” the domestic security chief, Hans-Georg Maaßen, told the DPA, voicing concern about the “increased aggressiveness” of its followers.