Madonna delivering a speech in support of the detained Pussy Riot band members, whom she described as "courageous" during her Olympiisky performance.
The same day that Madonna stood up for Pussy Riot punk rockers facing jail time over an anti-government performance, U.S. Embassy officials urged fans to be vigilant after receiving information regarding possible physical violence at Madonna's upcoming concert in St. Petersburg.
The concert, scheduled for Thursday, will take place at the northern capital's Petersburg Sports and Concert Complex as part of the U.S. pop star's promotion of her latest album MDNA.
Russian authorities have assured embassy officials that additional security measures will be in place for the performance, the U.S. Embassy said.
An embassy official reached by telephone Wednesday would not elaborate on the potential violence, but said that the U.S. Consulate in St. Petersburg had received the information Tuesday and that a statement had been posted on the embassy's website within hours.
The St. Petersburg show comes hot on the heels of a Tuesday evening performance at Moscow's Olimpiisky stadium, where no violence was reported. Moscow and St. Petersburg are the only two Russian cities where Madonna will perform during the world tour.
During the Olimpiisky show, Madonna paused between songs to express support for the three Pussy Riot band members currently standing trial on hooliganism charges in a Moscow courtroom.
"I just want to say a few words about Pussy Riot," Madonna said, according to a video of her speech posted on YouTube.
"I mean no disrespect to the church or the government, but I think that these three girls — Masha, Katya, Nadya — have done something courageous, have paid the price for their act, and I pray for their freedom."
The female rockers, who have been in detention since early March, face up to seven years in jail in a case that has split Russian society and drawn stinging criticism from abroad.
The charges relate to a February performance in Christ the Savior Cathedral, when masked band members sang a song criticizing President Vladimir Putin and Patriarch Kirill, the top Russian Orthodox official.
In a further gesture Tuesday, Madonna donned a balaclava — the Russian punk band's calling card — and removed her top, revealing the words "Pussy Riot" written on her back, to perform her 1984 hit "Like a Virgin."
Unlike the warm reception she received from fans, Russian Orthodox activists protested Madonna's performance by silently processing around the stadium carrying wooden crosses prior to the performance.
"We are simple Orthodox people, and we are taking a stand against Madonna and everything of that type," an activist told RIA-Novosti at the time.
Madonna, whose songs are still popular among many Russians who started listening to her music long before the Soviet collapse, has been the subject of controversy while performing in Russia on more than one occasion.
In 2006, for instance, radical religious activists called upon authorities to ban her concerts in Moscow, saying her songs promote religious hatred.