Pussy Riot lauded by Madonna at New York concert

Two formerly imprisoned members of the Russian punk group Pussy Riot were lauded by US pop star Madonna as they spoke at an Amnesty International concert on Wednesday.

Maria Alyokhina and Nadezhda Tolokonnikova called for the release of anti-government prisoners in Russia and thanked supporters for sending letters while they were in jail.

The two spent 16 months in prison after their arrest in August 2012 for singing a protest song in a Moscow cathedral.

They were freed last month in what they derided as a publicity stunt in advance of the Sochi Winter Olympics.

They were introduced by Madonna, who told the crowd she received death threats for backing Pussy Riot after several members were arrested.

"I've always considered myself a freedom fighter since the early '80s when I realised I had a voice and I could sing more than songs about being a material girl or feeling like a virgin," Madonna said.

Produced by Anna Bressanin