US singer Madonna performs in St. Petersburg (Reuters)

Madonna has been summoned by a court in St. Petersburg to appear on charges of breaking the city's anti-gay pro-propaganda law.

The singer has been sued by two anti-gay groups for 333m roubles (£6.7m), after she spoke out in support of gay rights during a concert in the north western Russian town in August.

A local law passed earlier this year bans public actions aimed at "propaganda of sodomy, lesbianism, bisexuality and transgenderism," that could "damage the health, moral and spiritual development of the under aged."

The regulation and carries a fine of up to 500,000 roubles ($16,100) but activists can also seek for moral damages in case of offence.

Pro-Kremlin group Trade Union of Russian Citizens believes Madonna "insulted believers' feelings," as "she promoted homosexuality when there were children at the concert," spokesperson Darya Dedova was quoted saying by Russia Today.

The summon was reportedly sent to Madonna's home address in New York City and calls for the "Material Girl" show up in court on October 25. Madonna was earlier expected to appear at a hearing on October 11 that she failed to attend.

Although homosexuality itself was decriminalised in the 90's, discrimination against gays and homophobic-related incidents are not unusual in Russia.

Earlier this year, one of the two anti-gay group that sued Madonna asked St Petersburg's prosecutors to initiate an investigation against PepsiCo under the same law, since one of the company's subsidiary brands, Happy Milkman, put a rainbow on its dairy products packaging.

The "controversial" carton showed the happy milkman on a green field with three coloured cows and a rainbow on the back. Activists from the organisation the People's Council, fund the bucolic image offensive given that the rainbow is the symbol of the LGBT community.

In another incident earlier this month in Moscow, a LGBT club hosting a "Coming Out" party, was attacked by a group of masked men. Three people were injured.

gay rights russia
A gay rights activist holds a board before a concert of pop star Madonna in St. Petersburg (Reuters)