Authorities have previously canceled concerts by Noize MC in the Russian cities of Samara, Kursk and Belgorod.

Authorities in Russia's southern city of Krasnodar will be scrutinizing a concert Friday by rapper Noize MC for signs of extremism after he criticized Russia's involvement in the Ukraine crisis at a performance in the region last year, regional prosecutors said in a statement Wednesday.

Noize MC, whose real name is Ivan Alexeyev, is one of Russia's best-known rappers and is outspoken in his liberal political views.

Prosecutors in Krasnodar have issued a warning to Friday's concert organizers that Noize MC should not be allowed to voice extremist views, the statement said, adding that during a performance in the region last August, the rapper had "expressed disagreement with Russia's position in respect to events occurring in Ukraine," where pro-Russian rebels have been fighting Ukrainian government troops for the last year.

Noize MC appeared on stage naked at a major music festival in the Krasnodar region last August in protest against his microphone being turned off when he started talking about Ukraine.

He reportedly told the crowd he had just been to Ukraine but had not seen any Nazis, a reference to repeated descriptions of the Kiev government as Nazis by Russian officials and media.

The police have been alerted to the possibility of extremist statements being made at Friday's concert, prosecutors said.

Authorities have previously canceled concerts by Noize MC in the Russian cities of Samara, Kursk and Belgorod, citing drug raids, the "possibility of a provocation" and "technical reasons," respectively.

Last year a group of Communist Party lawmakers called for performances by the rapper to be banned because of his apparent support for the new government in Kiev.

Russian Authorities to Monitor Noize MC Gig for Extremism Over Rapper's Stance on Ukraine