Madonna should be prosecuted for violating a Russian ban on public statements supporting homosexuality, an official in the city of St Petersburg says.
The US pop star wilfully violated city codes on "gay propaganda" when she took to the stage in the Baltic Sea port late Thursday, city council official Vitaly Milonov was quoted by the RIA Novosti news agency as saying.
Madonna and the concert organisers should be fined for her "illegal" statements at an event attended by people as young as 12, he said on Friday.
Witnesses were available to testify against the singer, Milonov added.
The St Petersburg city government would not permit "our society to be fed sewer water from the hellish kitchen of the evil empire," he said.
Madonna stripped down to her bra during the performance to reveal the words "No Fear" painted on her back.
She told her 25,000-strong audience she would speak out in support of homosexuality and other alternative lifestyles, even if laws banned such statements.
"Show your love and appreciation for the gay community! Are you with me?" Madonna said.
"All people should be treated with dignity, respect and love."
Deputy Prime Minister Dmitry Rogozin, who has frequently criticised Western social influences on Russian society, commenting on Twitter said: "What a has-been... in her old age she tries to lecture every one about morals. Especially when she is touring abroad."
In a performance in Moscow on Tuesday, Madonna called on authorities to release the three members of local punk band Pussy Riot who were put on trial after performing songs in a cathedral that were deemed to have been insulting to President Vladimir Putin.
