St. Petersburg's Prosecutor General's Office has declared the two pop icons violated the terms of their Russian visas by making money from their concerts. In a statement reported by RAPSI, the prosecutor claims "the visas issued were of the basic cultural exchange sort, which does not grant their bearers the right to engage in any commercial activity."

This is the latest in a series of legal attacks against the musicians in St. Petersburg, with the challenges being fronted by Vitaly Milonov - a vocal supporter of the city's 'anti-homosexuality' legislation. Milonov has already filed for action against Lady Gaga's November 2012 concert for 'promoting homosexuality' and slandering Russia. The anti-gay lobby tried similar legal action against Madonna for her gig earlier last year, but a city judge dismissed the challenge.

St. Petersburg has banned 'homosexual propaganda' since March 2012, and several gay rights activists have been arrested for protesting the law. 'Sister cities' LA and Manchester have urged St. Petersburg to drop the legislation, while Milan late last year suspended the 'special relationship' that had existed between the two cities on the back of the controversial law.