Madonna introduces Pussy Riot at star-studded sellout concert in NYC

Feted by Madonna and cheered by thousands, Russian punk protest group Pussy Riot defied President Vladimir Putin on the eve of the Sochi Olympics at a star-studded New York concert.

The performance highlighted soaring tensions between Russia and the United States, which drastically deteriorated when Moscow granted asylum to U.S. intelligence leaker Edward Snowden last year.

Ppop icon Madonna hailed the courage and fearlessness of punk heroines Maria Alyokhina, 25, and Nadezhda Tolokonnikova, 24, who were released from Russian penal colonies last December.

Madonna said she was threatened with death after supporting them at a concert in Moscow during their trial in August 2012 and accused by Russian authorities of propagating homosexual behavior.

"It's time for the rest of the world to be as brave as Pussy Riot and to stand up against people like President Putin and other leaders and other organizations that do not respect human rights and perpetuate discrimination and injustice," Madonna said.

"It is my privilege and my honor, ladies and gentlemen, to introduce Masha and Nadya from Pussy Riot," she shouted over cat calls as the ecstatic Barclays Center in Brooklyn went wild.

"Can we get a 'hell yeah,'" she bellowed, dressed in a black woolly hat and long black coat before embracing the two women on stage.

Wearing black blazers, ankle boots and white tunics with black crucifixes emblazoned on the front, Alyokhina and Tolokonnikova delivered a furious and emotional rebuke of the Putin regime.

"We will not forgive and we will not forget what the regime is doing to our fellow citizens. We demand a Russia that is free," Tolokonnikova told the crowd.

"Now Russia will be free," the pair chanted, thanking Madonna and saying they were "overjoyed" by her support.

The duo were sentenced to 21 months in jail for hooliganism after performing a stunt inside a Moscow cathedral.

Although the stunt was unpopular among ordinary Russians, their trial and sentence turned them into dissident stars in the West.

They were released two months early in December as part of a pre-Sochi amnesty. But they have vowed no let up in their campaign against Putin's crackdown on civil liberties.

Organized by Amnesty International, Wednesday's concert whipped up a crowd of thousands crammed into one of New York's largest music and sporting venues with a maximum capacity of 18,000.

Blondie, fronted by a still electric Debbie Harry, brought the house down with their hits "Call Me" and "One Way or Another."

U.S. pop and rock bands Imagine Dragons, who also paid tribute to Pussy Riot, Flaming Lips, Cake, the Fray and Cold War Kids fired up the crowd who danced and cheered from their seats.

Grammy-winning American soul singer Lauryn Hill, who spent three months in a US prison last year for failing to file her tax returns, also performed a set to wild cheers from loyal fans.

U.S. actress Susan Sarandon introduced the concert and there were pre-taped messages from the likes of Peter Gabriel and Sting.

The Sochi Winter Olympics have opened up a new front of distrust between the United States and Russia, and tensions over security preparations amid fears the games could be attacked by extremists.

They are the first Olympics held in Russia since the US boycotted the 1980 Moscow Games because of the Soviet invasion of Afghanistan and have added to the host of issues, including the Syrian civil war, that have divided the countries.

Relations reached a nadir last summer after Moscow gave asylum to Snowden and President Barack Obama scrapped a planned visit.

Moscow also reacted angrily to US charges in December against 49 current and former Russian diplomats and their wives for fraud.

Amnesty says that Pussy Riot represent a young generation of Russians standing up to repressive laws introduced under Putin.

Irish singer Bob Geldof called on a younger generation of Americans to campaign for human rights and blasted through his "I Don't Like Mondays" hit to a dwindling audience.

Speaking earlier, he compared Pussy Riot to the Sex Pistols and urged people to take a stand about rights issues in general.

"I hope tonight it's not all gloopy and American and gets straight to the heart of the matter," Geldof told AFP.