If all publicity is good publicity, then “Matilda”, a new film about Russia’s last tsar, should be on track to be a box office hit.

But as next month’s international release date approaches, the movie’s backers are facing an increasingly virulent campaign for it to be banned.

Orthodox Christian activists have led nationwide protests calling the film “blasphemous” and “a slap in the face to Russian nation”. The director’s studio has been firebombed and Russia’s largest cinema chain now says it won’t show the film because of security fears.

The film — which tells the true story of Nicholas II’s love affair with a teenage Polish ballet dancer – has poked a central nerve among the standard-bearers of Russia’s Orthodox and traditionalist post-Soviet identity. It is a vision that President Vladimir Putin has himself encouraged, and many of those advocating the ban are his natural supporters. Yet for the moment, the Kremlin is staying above the fray - biding its time, some speculate, in the hope of using this clash of narratives for its own ends.