Orthodox extremists have been arrested in Russia for arson attacks and death threats as part of their campaign against 'Matilda', a forthcoming film about the affair between a ballerina and Tsar Nicholas II, considered a martyr by the Orthodox church.

Alexander Kalinin, the leader of the hardline Orthodox Christian group, which calls itself 'Christian State - Holy Rus' was one of those arrested. Kalinin and others are suspected of committing arson on several cinemas as well as offices and studios used by to the film's director, Alexei Uchitel.

In one incident, a car filled with gas cannisters was driven into the entrance of a cinema in Yekaterinburg, the town in which the Tsar and his family were executed by the Bolsheviks, causing it to catch fire.

The Interior Ministry spokesperson, Irina Volk, explained to Russia's Interfax news agency yesterday: 'We've opened a criminal case on charges of coercion. Attempts have been made to force managers of a commercial screening organisation to refuse to show this film under threats of violence against the audience and damage and harm to cinema owners'.

These threats have not been without effect. After 'Christian State-Holy Rus' penned an open letter in which they warned of civil war, and declared that its members were ready to sacrifice their lives 'for the true Orthodox Christian faith', Russia's largest cinema chain, Cinema Park and Formula Kino, said they decided earlier this month to not screen the film in 28 cities to 'protect cinema-goers from risk'.

Although Russia's Culture Ministry approved the film in July, Natalya Poklonskaya, a State Duma MP linked to President Vladimir Putin's United Russia party, has also demanded the film be banned for its offensiveness to Orthodox Christians.

The film is based on the memoirs of the Polish-Russian Matilda Krzesinska (1872-1971), who had an affair with the Tsar before marrying his cousin, Grand Duke Andrei Vladimirovich Romanov. Some Orthodox Christians feel that the film will besmirch the memory of Nicholas II, who was declared a saint, or passion-bearer, by the Moscow Patriarchate in 2000.

The year of the film's release is also significant as 2017 marks the centenary of the 1917 Bolshevik Revolution which dismantled the Tsarist regime, ultimately leading to the execution of the Tsar and his family. For Russian Orthodox leaders, this year will also be commemorated as the beginning of the church's Soviet-era persecution.