"The Pirates can't allow themselves to fall victim to a general right-wing extremism in society," Renate Künast, head of the Green parliamentary party told the Frankfurter Rundschau newspaper on Saturday.
The upstart Pirate party, known for its free speech platform, sailed into troubled waters this week after failing to dismiss party member Bodo Thiesen for his comments relativising the holocaust and defending convicted Holocaust denier Germar Rudolf in a Youtube video in 2008.
"We're astonished," Heinz Bierbaum Vice President of the Left party told the paper on Wednesday. "Whoever shows understanding for holocaust deniers and rejects German guilt for the Second World War isn't acting on the grounds of freedom of speech but rather is falling into a brown swamp."
Pirate Party Leader Sebastian Nerz defended the party's position in the Bild am Sonntag paper on Saturday, pointing to a "clear commitment against right-wing extremism and racism" in the party statute.
He admitted however to not stepping in fast enough to distance the party from Holocaust deniers.
At the same time Nerz defended the decision made by the party arbitration commission on Monday that Thiesen should not walk the plank as he had already received official warning for his comments.
"Under the basic principles of the law you can't punish someone twice for the same offence," he told the paper.
But there is mutiny afoot as other Pirate leaders have distanced themselves from the decision.
"I expect the Pirates to make Bodo Thiesen's existence in the party unpleasant," Martin Delius, state secretary of the Pirate Party in the Berlin state parliament - where the Pirates currently hold 15 seats - told the Berliner Zeitung newspaper on Wednesday.
At the same time the party admitted to a problem with right-wing sentiments among members, with Delius referring to "other crazy people in the party."
"I recognize we have a Nazi problem in the Pirates," head of the Berlin Pirate Party Hartmut Semken told the paper on Thursday.
"There's no alternative: a party which accepts members without any pre-screening can't help but attract people trying to hide their contempt for humanity behind freedom of expression," he added.
Semken is now facing calls from within the party to step down after comparing Pirate election campaign methods in Berlin with those of the Nazis.
The Green party, who last week said they would not rule out forming a coalition with the Pirates, are especially disturbed by this week's events.
The Pirates "can't be open to everything in every question," Künast told the Frankfurter Rundschau on Saturday. Otherwise they will be accepting and welcoming right-wingers into their crew.