Britain’s Pet Shop Boys, Pulp and The Who on Thursday declared their support for Russian punk band Pussy Riot and urged Russian President Vladimir Putin to see to it that the band members get a fair trial.

Three Pussy Riot members - Nadezhda Tolokonnikova, 23, Maria Alyokhina, 24, and Yekaterina Samutsevich, 29 - are on trial in Moscow over their alleged performance of a “punk prayer,” calling for then-Prime Minister and United Russia head Vladimir Putin to quit. They face up to seven years if convicted on hooliganism charges.

In a letter to The Times, Jarvis Cocker, Pete Townshend, Martha Wainwright, Neil Tennant, Johnny Marr and other musicians expressed their "legitimate protest" to Putin, who is currently in London for the Olympic Games.

They said they were "extremely concerned" over the way Pussy Riot members have been treated in custody and demanded their release.

During the hearings on Wednesday, all of the three women felt sick and ambulances were called several times, their lawyer Nikolai Polozov said. One of the accused was given an injection for her low blood-sugar levels and doctors later said the trial could resume.

"We are especially concerned about recent reports that food is being withheld from them and that they have appeared in court in a cage," the letter said.

"We believe firmly that it is the role of the artist to make legitimate political protests 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."

Members of Pussy Riot have called their “punk prayer” in Moscow’s Christ the Savior Cathedral earlier this year an “ethical mistake,” but pleaded not guilty to charges of hooliganism.

Amnesty International has recognized the three group members held in custody as prisoners of conscience. A number of prominent Western musicians, including Sting, Franz Ferdinand and the Red Hot Chili Peppers, have spoken in their support.