BERLIN — Two German theater directors called on Russian authorities Sunday to drop a criminal investigation of a Russian director who has been put under house arrest for allegedly embezzling government funds.

German theater director Thomas Ostermeier and director and playwright Marius von Mayenburg were circulating a petition on behalf of Kirill Serebrennikov, the Russian theater and film director who has maintained his innocence.

They also appealed to the German government “to ensure that Serebrennikov doesn’t become the victim of a politically motivated defamation of character and doesn’t end up in prison.”

The petition was signed by Australian actress Cate Blanchett and German film director Volker Schloendorff among others.

Serebrennikov appeared in court Wednesday and was placed under house arrest pending an investigation into charges that he embezzled government funds allocated for one of his projects.

The director denies any wrongdoing, and the case against him is widely seen as part of a crackdown on freedom of expression in Russia.

“This is in effect a communication ban, a prejudgment and a prohibition to work for one of the most famous contemporary Russian artists,” the two Germans wrote in their petition, referring to the Russian director’s arrest.

Serebrennikov’s sold-out shows have been a key part of Moscow’s theater scene for years. His cutting-edge productions include drama, opera and movies. He has won broad acclaim for satires mocking official lies, corruption and a growing hard-line streak in Russian society.

In September, he was to direct an opera in Stuttgart, Germany.