Bayern Munich president Uli Hoeness has urged German football clubs to fight the threat of right-wing extremism in stadia.
During a discussion on the issue on Wednesday, Hoeness warned that vigilance was needed and said Bayern "would not tolerate" such behaviour.
"Over the past ten years, we have succeeded in forcing the culture out of the stadium by isolating it," he told the Deutschlandfunk radio station after the discussion.
"FC Bayern does not want a right-wing mindset. FC Bayern does not put up with it and does not accept it."
Speaking to Sky, he explained that, with the help of police and supporters' organisations, Bayern had been able to eliminate right-wing factions from the Allianz Arena support.
But he added: "One should never act like the wise guy and always mind his own business."
He said other clubs, especially in the east of Germany, needed to act and mentioned recent instances of right-wing problems at Borussia Dortmund.
"When you confront Mr [Hans-Joachim] Watzke [the Dortmund CEO] with it, he gets pretty angry," he said. "But it also applies there. You have to concentrate on taking on the issue."
Hoeness also said he hoped the German Football League and the German Football Association would increase their co-operation to help root out right-wing extremists.