MOSCOW (AFP) ― Over 100 of Russia’s best known actors, directors and musicians on Wednesday called for the release of three young women detained after singing an anti-Vladimir Putin song in a Moscow church.

Nadezhda Tolokonnikova, Yekaterina Samutsevich and Maria Alekhina from the punk rock group Pussy Riot have been held in pre-trial detention since March for their performance of a “punk prayer” in the Church of Christ the Saviour.

“We do not see any legal foundation or practical sense in further isolating from society these young women who present no real danger,” said the letter, published in the Moskovsky Komsomolets daily and signed by 103 artists.

The signatories included well-known opponents of President Putin like the detective author Boris Akunin, poet Dmitry Bykov and rock singer Yury Shevchuk.

But also signing were much-loved actress Chulpan Khamatova and prominent actor Yevgeny Mironov, who both controversially appeared in videos earlier this year urging Russians to vote for Putin in the March elections.

In a virtual who’s who of the Russian cultural elite, other prominent names included the film director Andrei Konchalovsky, the ballet dancer Nikolai Tsikaridze and the composer Leonid Desyatnikov.

“We believe that the actions of Pussy Riot are not criminal. The girls killed no-one, stole from nobody, carried out no violence,” said the letter which was also published on the website of popular radio station Moscow Echo.

“Russia is a secular state and no anti-clerical actions ― as long as they are not a violation of the criminal code ― can be a reason for criminal prosecution.”

The imprisonment of the trio has turned into a rallying cause for the opposition movement against Putin, with supporters arguing that even if their action was not appropriate the punishment is cruelly disproportional.

“We believe that the criminal case against Pussy Riot compromises the Russian judicial system and undermines trust in the authorities as a whole,” the letter said.

It warned: “While the participants in the action have been held under arrest, an atmosphere of impatience has grown in society which will cause division and radicalism.”

The letter comes after a court last week extended the trio’s detention until July 24. A trial is not expected to begin any earlier than August.

The young women, two of whom have children, are charged with hooliganism by an organised group, an offence which carries a maximum jail term of seven years.

In February, the group shocked worshippers by climbing into an area reserved for priests and singing a song criticising the Russian Orthodox Church’s close ties to the Kremlin.