LONDON (Reuters) - A Russian theatre director and playwright told a court on Monday they were not guilty of charges of justifying terrorism on the first day of their trial over the staging of an award-winning play, Mediazona reported.

Director Zhenya Berkovich and playwright Svetlana Petriychuk were arrested in May last year for putting on "Finist, the Brave Falcon", which tells the story of Russian women who married Islamic State fighters.

The case has become a focus for fellow artists, human rights defenders and free speech campaigners, with an open letter in their support garnering more than 16,000 signatures.

Russian film director Kirill Serebrennikov used his appearance at the Cannes Film Festival on Monday to protest against the proceedings.

The two women told a Moscow military court they had set out to advocate against terrorism, not to support it, according to a transcript of the hearing published by independent outlet Mediazona, which reports on Russian trials.

"I staged the performance to prevent terrorism," Berkovich, 39, told the court, Mediazona reported. Towards terrorists, she said, "I have nothing but condemnation and disgust".

Petriychuk, 44, echoed Berkovich and denied any guilt.

"It is unlikely that Islamic radicals would use modern theatre to promote their ideas, because they sort of forbid these types of art," she said, according to the report.

Last month the pair were added to Russia's official list of "terrorists and extremists", joining many thousands of people and entities who have been similarly designated in a crackdown on perceived subversive activity that intensified after Russia launched its full-scale invasion of Ukraine in 2022.

The Kremlin does not comment on individual cases but says Russia is engaged in an existential struggle with the West and needs to robustly uphold its laws and defend itself.

The offence of providing justification for terrorism can lead to up to seven years in prison.

More people have been prosecuted in Russia in the past six years than in the almost 30 years under the rule of Soviet leaders Nikita Khrushchev and Leonid Brezhnev, according to data analysed by independent outlet Proekt.

(Writing by Lucy Papachristou; Editing by Andrew Heavens)

By Lucy Papachristou