By Liza Dobkina

ST PETERSBURG, Russia, Aug 9 (Reuters) - Pop star Madonna spoke out for gay rights at a concert on Thursday in St Petersburg, Russian President Vladimir Putin's home town, where activists say a law adopted this year to curb homosexual "propaganda" is discriminatory.

Performing in black lingerie with the words "No Fear" scrawled on her bare back, Madonna urged the audience - most wearing pink wrist bands distributed at the door - to "show your love and appreciation to the gay community".

"We want to fight for the right to be free," she said.

The American singer has turned a two-concert tour into a platform for comment on Putin's Russia.

In Moscow on Tuesday, she told a crowd she prays for the release of three members of the band Pussy Riot, who prosecutors want jailed for three years for their "punk prayer" criticising Putin on the altar of Russia's main cathedral.

She told Reuters Television that the three women, whose trial verdict is to be announced on Aug. 17, had been treated unfairly and suggested they were victims of censorship.

Madonna had promised to use her St Petersburg show to speak out against legislation adopted by the city in March that imposes fines for spreading homosexual "propaganda" that could "damage the health, moral and spiritual development" of minors.

On her Facebook page, she called the law a "ridiculous atrocity".

Critics of the law - the model for a bill submitted to the national parliament - say they fear it could be used to clamp down on the lesbian, gay, bisexual and transgender community, for instance by barring gay rights demonstrations.

St. Petersburg police chief Sergei Umnov told local reporters in July that 74 people had been fined so far.

Homosexuality, punished with jail terms in the Soviet Union, was decriminalised in Russia in 1993, but much of the homosexual community remains largely underground as anti-gay prejudice runs deep.

Numerous attempts to hold gay protests in Moscow, ruled illegal by the authorities, have ended in arrests and clashes with violent Russian Orthodox believers who say homosexuals should be punished or treated for "illness".

"Do we live in fear?" Madonna asked her audience on Thursday night. "No!" came the reply. "We love you!" shouted some fans, but not everybody was thrilled.

"One should not mix showbusiness with human rights activism," said gay rights activist Yuri Gavrikov, who picketed the concert venue. "If she wanted to support the LGBT community, she could have ... refused to hold concerts in Russia."

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  • 'Like A Virgin' (1984)

    It was the performance that shook that world: a barely-known Madonna opened the very first MTV VMAs with her now legendary "Like A Virgin." She now says her rolling around on the floor was a cover-up to retrieve a lost shoe.

  • 'Into The Groove' (Live Aid, 1985)

    Madge performed her "Desperately Seeking Susan" soundtrack smash before an audience of 30,000.

  • 'Express Yourself' (MTV Video Music Awards 1989)

    Take that, Lady Gaga: Madonna offered a sneak peak at voguing when opened the 1989 VMAs with this female empowerment smash.

  • 'Vogue' (1990 MTV Video Music Awards)

    The Material Girl set a new standard for live MTV performances when she ditched the fashion runway grab of the "Vogue" video for a Marie Antoinette look.

  • 'Sooner Or Later' (1991)

    Madonna shunned detractors who had long been critical of her live vocals when she nailed every note of this Stephen Sondheim-penned "Dick Tracy" number to absolute perfection.

  • 'Bad Girl' ('Saturday Night Live,' 1993)

    Madonna's performance of this poignant ballad off the underrated "Erotica" album was undoubtedly a highlight of her SNL appearance.

  • 'Fever' (Arsenio Hall Show, 1993)

    Her own version may have been more dance-oriented, but Madonna brought her cover of "Fever" back to its classic Peggy Lee origins on Arsenio.

  • 'Bedtime Story' (Brit Awards 1995)

    Madge went from "Material" to ethereal when she opted for a Donatella Versace look for her Brit Awards performance in 1995.

  • 'Music' (Grammys 2001)

    Madonna struck a few pimp daddy poses for her second Grammy Awards performance, nearly 20 years into her career.

  • 'Imagine' (Tsunami Aid 2005)

    Madonna boldly covered the John Lennon classic for this performance, a fundraiser for the victims of the devastating 2004 Indian Ocean earthquake and tsunami.

  • 'Feel Good Inc. & Hung Up' (Grammys 2006)

    This wildly trippy performance of Madonna's "Confessions on a Dancefloor" hit featured Madge as a hologram alongside Gorillaz before the real thing emerged.

  • 'Like A Prayer' (Hope for Haiti, 2010)

    Madge brought back her 1989 classic for this truly stunning performance during the Hope For Haiti telethon.

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