Two members of the punk band Pussy Riot were attacked by unidentified men who doused them with green-coloured chemicals on a trip to campaign for prisoners' rights.

Nadezhda Tolokonnikova and Maria Alekhina, who spent nearly two years in prison for their irreverent protest against President Vladimir Putin in Moscow's main cathedral, were doused with green antiseptic Thursday by five men in a McDonalds restaurant in the Volga River city of Nizhny Novgorod.

In a video Tolokonnikova posted Twitter, the men also shouted insults, urging the women to leave the city. Tolokonnikova and Alekhina were trying to visit a local prison as part of their campaign to defend prisoners' rights.

Last month, Cossack militia attacked them with horsewhips when they tried to perform a song mocking Putin at the Sochi Olympics.