The United States embassy in Moscow has issued a security alert to Madonna fans in Russia.

It comes after the singer spoke out in support of a Russian punk band who are facing up to 7 years in jail for criticising Vladimir Putin.

‘Pussy Riot’ staged a protest in the largest Russian cathedral 2 weeks before the election which saw Putin returned as President.

Madonna says the feminist rockers should be treated leniently.

The American embassy says the Consulate-General in St. Petersburg has received information regarding a threat of physical violence against spectators and performers at the Moscow concert tonight.

Russian authorities have indicated they are taking appropriate measures in light of the information.

The embassy added “While we expect that enhanced security measures will be put in place at both concerts, U.S. citizens are reminded to remain vigilant regarding their personal security, and to be aware of their surroundings at all times, especially in crowded areas”.

She is also due to play in St. Petersburg on Thursday as part of her MDNA tour.