Police raided 141 clubs and homes Thursday, Der Spiegel reported. State Interior Minister Ralf Jager announced that three groups he described as "xenophobic, racist, anti-Semitic" have been banned.
"The members and supporters of the banned organizations reject our democracy and the established legal order," Jager said.
The groups had been preparing for Sept. 1 anniversary of the day Adolf Hitler launched World War II. Traditionally, neo-Nazis in North Rhineland-Westphalia have marked the day with a rally in Dortmund.
Authorities say there are 400-600 violent neo-Nazis in the state, which has the biggest population in Germany. Jager said there also appears to be more people interested in programs designed to help neo-Nazis leave their groups.
About 900 police officers participated in the raids, seizing weapons that included guns, brass knuckles, clubs and switchblades. Jager said no arrests were made.
Papers were served notifying the organizations of the ban.