Music stars including Pulp frontman Jarvis Cocker, The Smiths' Johnny Marr and Franz Ferdinand's Alex Kapranos have called for the release of Russian punk rock band Pussy Riot - who insulted President Vladimir Putin.
The three women led a "punk prayer" in Russia's main cathedral where they called on the Virgin Mary to "throw Putin out". They have been charged with "religious hatred" in a case which has split Russia.
In a letter to the Times, Cocker, Marr and Kapranos, along with others including singers Martha Wainwright, Pet Shop Boys' Neil Tennant, The Who's Pete Townshend, Corinne Bailey Rae and Kate Nash, said: "We are extremely concerned about the treatment they have received since their arrest and during their trial.
Members of feminist punk group Pussy Riot stand behind a glass wall at a court in Moscow, Russia
"We feel that a minor breach of the peace for an incident at the Cathedral of Christ the Saviour in Moscow in February was a legitimate protest.
"Dissent is a right in any democracy and it is entirely disproportionate that they face seven years in jail for what we consider to be a preposterous charge of "hooliganism motivated by religious hatred.
"We are especially concerned about recent reports that food is being withheld from them and that they have appeared in court in a cage.
"We believe firmly that it is the role of the artist to make legitimate political protest and fight for freedom of speech.
"As he visits the United Kingdom this week, we ask President Putin to ensure these three women receive a fair hearing."
The Russian president is in London on Thursday to meet Prime Minister David Cameron for talks on Syria - and to watch the Olympic judo.
Campaigners have urged the prime minister to bring up Russia's human rights record.
Pulp's Jarvis Cocker is one of the music stars who have called for the release of Pussy Riot
Singer Nash ran a competition on her Twitter page for campaigners to design posters to "Free Pussy Riot".
And even News Corporation's Rupert Mudoch urged Londoners to protest against the trial during Putin's London visit.
The stunt, by Pussy Riot members Maria Alyokhina, 24, Nadezhda Tolokonnikova, 22, and Yekaterina Samutsevich, 29, was designed to highlight the close relationship between the Russian Orthodox Church and Putin, who was then prime minister but later elected president.
In court this week, Tolokonnikova said in a statement: "We are not enemies of Christianity. The opinion of Orthodox believers is important to us and we want all of them to be on our side - on the side of anti-authoritarian civil activists.
"Our performance contained no aggression toward the public - only a desperate desire to change the situation in Russia for the better."
Alyokhina said in her prepared statement: "I thought the church loved all its children, but it seems the church loves only those children who love Putin."
Amnesty International has said the prison terms the women face are "wildly out of all proportion" and have called for the band members to be immediately released.