VATICAN CITY (AFP) - A topless feminist activist staged a lone protest on the edge of St Peter's Square on Tuesday as cardinals began a conclave to elect a new pope.

"Pope No More!" the young woman shouted, before she was dragged away by several police officers.

The woman had "Paedophilia No More" scrawled on her bare chest and "Pope No More" on her back.

She also let off a pink flare - a parody of the white smoke from the roof of the Sistine Chapel that will signal a pope has been elected.

The woman, who said she was from the Ukrainian group Femen, was detained and taken to a local police station near the famous Vatican plaza.

The Femen women's power group has been making headlines since 2010 for topless feminist, pro-democracy and anti-corruption protests.