Madonna is to be sued for $10m by a group of Russian campaigners after she spoke out in favour of gay rights at a gig in St Petersburg last week.

Ten anti-gay activists have filed a lawsuit, claiming the superstar ‘insulted their feelings’ when she attacked a city law which imposes fines for spreading homosexual propaganda.

One of the campaigners, Darya Dedova, said: "She had been warned with words that she should behave in line with the law and she ignored it. So we will speak in the language of money.

"Of course, it is difficult to measure moral damages and suffering but maybe people who earn money regardless of moral rules will better understand this."

Another activist, Alexei Kolotkov, added: "Maybe someone does not see the link but after Madonna's concert maybe some boy becomes gay, some girl becomes lesbian, fewer children are born as a result and this big country cannot defend its borders - for me it causes moral suffering."

Last week, the city leader Vitaly Milonov requested for the Material Girl to be prosecuted for the same reason.