Two members of the Russian punk band Pussy Riot took part in the Amnesty International's ''Bringing Human Rights Home'' concert in the Brooklyn borough of New York Feb. 5.

After being introduced by Madonna, Nadezhda Tolokonnikova thanked her and the audience in Russian for the support, criticized Vladimir Putin and demanded more freedom in Russia.

While in the United States, the women plan to visit prisons and meet with related non-governmental organizations to gain insight into how the Russian prison system might be improved.

Before speaking at the concert, the pair met with U.S. Ambassador to the United Nations Samantha Power to discuss their time in jail. The meeting took place at the U.S. mission to the United Nations.

When asked about Power's roughly half-hour meeting with the Pussy Riot members, Russian Ambassador to the U.N. Vitaly Churkin said: "She has not joined the band? I would expect her to invite them to perform at the National Cathedral in Washington. Maybe they could arrange a world tour for them, you know. St Peter's Cathedral in Rome, then maybe in Mecca in Saudi Arabia, ending up with a gala concert at the Wailing Wall in Jerusalem. So if Ambassador Power fell short I would be disappointed.”

Power struck back at Churkin on Twitter on Wednesday night, writing “I'd be honored to go on tour with Pussy Riot — a group of girls who speak up & stand for human rights. Will you join us? I can't sing, but if Pussy Riot will have me, Amb Churkin, I say our 1st concert is for Russia's political prisoners live from Matrosskaya Tishina prison.”

Six other members of Pussy Riot have criticized the New York concert.

In a letter posted on the group's blog on Feb. 6, the anonymous members reminded organizers that Tolokonnikova and Alyokhina had publicly quit the group, choosing instead to pursue a human rights agenda.

“Yes, we’ve lost two friends, two ideological supporters, but the world got two brave, interesting human rights activists who fight for imprisoned in Russia. Unfortunately we can congratulate them face to face, because they are avoiding any contacts with us. But we respect their decision and choice and sincerely wish them good luck.”

The letter also criticized a concert poster featuring a male guitarist in a balaclava, a group trademark, and said selling tickets was contradictory to Pussy Riot's principles.

"We only stage illegal performances in unexpected public places," the letter said.

U.S. tour was made possible with the support of the Amnesty international.

During their time Tolokonnikova and Alekhina also went to the office of the New York Times office and appeared on The Colbert Report.

Based on materials from Radio Free Europe/Radio Libery and Reuters.