Russia’s culture minister has fired the director of a Siberian theatre whose modern staging of Wagner’s opera Tannhauser offended the powerful Russian Orthodox church.

The announcement that Boris Mezdrich had been sacked was made on Sunday as several thousand people rallied outside the Novosibirsk theatre to protest against the opera, which they said was offensive to Christians and reflected the values of the decadent west.

“Orthodox Christianity is the foundation of the great Russian culture,” said one of the signs held by the protesters in Novosibirsk, a city of 1.5 million and the third-largest in Russia.

They waved patriotic flags, including some with a picture of President Vladimir Putin imposed upon the Russian tricolour and others in the orange and black stripes of the St George ribbon. Long associated with commemorations of the victory in the second world war, the ribbon is now worn to express support for the Russia-backed separatists fighting in Ukraine.

The Russian Orthodox church has played an active part in Putin’s efforts to consolidate Russian society by appealing to what are described as traditional Russian values as opposed to western liberalism.

As the controversy over Tannhauser grew in recent weeks, many Russian cultural figures spoke out in defence of the theatre’s interpretation of Richard Wagner’s 19th-century opera.

But on Sunday, the culture minister, Vladimir Medinsky, fired Mezdrich as director of the Novosibirsk state opera and ballet theatre, a position he held between 2001 and 2008, and since his reappointment in 2011.

Medinsky replaced him with Vladimir Kekhman, director of the Mikhailovsky theatre in St Petersburg. Kekhman told the state news agency Tass that he would remain director of both theatres.