Russian punk protest group Pussy Riot took their campaign against Vladimir Putin's civil liberties crackdown to New York, where they are to tread the same stage as Madonna. The US pop superstar will on Wednesday introduce Maria Alyokhina, 25, and Nadezhda Tolokonnikova, 24, at a star-studded Amnesty International concert featuring Bob Geldof and Blondie. The United States is the latest stop on a whirlwind international tour that has taken them to Asia and Europe since their release from a 21-month jail sentence in Russia last December. Their protest stunt inside a Moscow cathedral, subsequent trial and imprisonment has jettisoned the attractive women into symbols of bravery and peaceful dissent in Russia, much admired abroad. They have vowed to use their freedom to found a human rights organization, speaking out for feminism, gay rights, political transparency and better treatment for prisoners. At a news conference at Amnesty's New York offices, they were asked what they would like to say to US President Barack Obama and Putin. Tolokonnikova was succinct. She appealed on Obama "not to be afraid to publicly say your thoughts about what you feel is happening in Russia once you are there during your next visit." "The question for Vladimir Putin is: aren't you sick of it all?" Her remarks were translated by her husband, Pyotr Verzilov. With the Sochi Winter Olympics kicking off on Friday, the women repeated their mantra for foreign visitors not to forget problems in Russia papered over by the festivities. "We would like for Americans to really look at Russia and see Russia beyond the images of Olympics objects and buildings," Alyokhina said. "These objects have no relationship to Russia. They are foreign objects in Russia," she added. The two activists are to share a stage with Madonna at the Barclays Center in Brooklyn on Wednesday when they will read a speech about human rights challenges in Russia. Madonna backed the women at a concert in Moscow during their trial in August 2012, stripping to reveal "Pussy Riot" written on her back and saying she had prayed for their release. Their controversial stunt took place inside Moscow's Christ the Saviour Cathedral in February 2012. The women, who have young children, were sent to penal colonies after being convicted on a charge of hooliganism motivated by religious hatred for their anti-Putin song in the cathedral. On Tuesday they thanked Amnesty for supporting them with letters during their time in prison. "What makes you keep on living, even when you're behind prison bars, is that feeling of solidarity and compassion that goes through even thick prison walls," Tolokonnikova said. A third member of the group, Yekaterina Samusevich, 31, was released in October 2012 after being given a suspended sentence.