Folk veteran Joan Baez has urged her fans to sign a petition calling for the freedom of jailed Russian rockers PUSSY RIOT.

Support freedom of expression. Free Pussy Riot!

Three stars of the band are behind bars awaiting a court verdict on charges of hooliganism after they performed a protest song aimed at President Vladimir Putin at a church in Moscow earlier this year (12).

Madonna, Paul McCartney and Bjork have already thrown their weight behind a campaign to free the trio, and now Baez has added her support.

She has taken to her Twitter.com page to highlight the case, and links to a petition launched by Amnesty International calling for the rockers' release.

In a post, she writes, "Support freedom of expression. Free Pussy Riot!" The stars are due to be sentenced on Friday (17Aug12).