It is Iran’s answer to Cannes, Venice and Berlin rolled into one. The cinematic and cultural highlight of the Islamic republic’s calendar, the annual Fajr festival in Tehran is a 10-day extravaganza of film, drama, poetry and literature. This year’s event, which opens on Monday, ought to be a magnet for the country’s artistic elite and a host of international stars.

But Ken Loach and the British theatre director Peter Brook are among leading Western artistic figures who have informed the Islamic regime they are pulling out in protest at its brutal crackdown on the opposition, which includes torture, prison rapes, countless killings and Stalinist-style televised show trials of reformists.

The boycott is a response to a plea by Iranian artists. A joint statement from Iranian cinematographers, playwrights and actors, unsigned to protect those still working in the country, had circulated in recent weeks urging their foreign counterparts to stay away from Tehran to avoid conferring respectability on President Mahmoud Ahmadinejad’s government. “Your presence in this year’s Fajr festival will be akin to ignoring the struggles of oppressed people of Iran for their rights,” the statement said. A number of leading Iranian cinema figures including Abbas Kiarosami have already turned down invitations to be on the festival’s jury.