The CSU aims to ban foreign funding of German mosques to stave off extremism. The proposal has Muslim supporters, but opponents say the regulation violates a key constitutional right.

The sister party of Chancellor Angela Merkel’s CDU has called for stricter regulations of Islam in Germany. CSU General Secretary Andreas Scheuer laid out his proposals in an interview with German daily “Die Welt” that was published on Wednesday.

“German must become the language of the mosques,” Scheuer said in the conversation that covered integration issues, among other topics.

No more training or money from abroad