German police have raided sites across the country linked to a banned far-right group, weeks after a suspected extremist shot dead nine people of migrant backgrounds.

An interior ministry spokesman said raids were being carried out in 10 of Germany’s 16 states.

“For the first time, the interior minister has banned a Reichsbürger (Citizens of the Reich) group,” the spokesman said. “Even in these times of crisis, we will fight far-right extremism, racism and antisemitism.”

The United German Peoples and Tribes organisation banned on Thursday belongs to the wider Citizens of the Reich movement, which is fed by conspiracy theories.

Its adherents question the legitimacy of the modern Federal Republic of Germany and have in the past entered into armed confrontations with police. In 2016 a man linked to Citizens of the Reich killed an officer and wounded two more in a shootout. He was later sentenced to life in prison.

After a racist gunman shot dead nine people of migrant backgrounds in the city of Hanau last month, Germany’s interior minister, Horst Seehofer, declared far-right extremism “the biggest security threat facing Germany” and announced increased police measures.

Seehofer said the far right had left “a trail of blood” in recent months. Two people died in an attack on a synagogue in Halle in October and a pro-migrant politician was murdered at his home last June.

Separately, in February 12 men were arrested across Germany on suspicion of planning attacks on mosques aimed at bringing about “a civil-war-like situation”.

The government has announced hundreds of new posts for federal police and security services to strengthen surveillance of the far-right scene, and it is considering tighter laws on gun ownership.