ST. PETERSBURG, Russia (AP) — About 20 Orthodox believers in Russia have sung prayers to protest the release of a movie about the last Russian czar's affair with a ballerina.

They gathered outside the Mariinsky Theater in St. Petersburg, where "Matilda" was shown Monday to a selected audience ahead of its release this week.

The film loosely tells the story of Nicholas II's infatuation with ballerina Matilda Kshesinskaya.

It has angered hard-line nationalists, and some Orthodox believers see it as blasphemous. The czar is glorified as a saint in the Russian Orthodox Church.

Nicholas and his family were executed by Bolsheviks in 1918.

Police last month detained several activists accused of setting cars on fire outside the office of the attorney for the film's director. Someone also tried to set fire to the director's studio.