'Pope No More!' Femen vs Vatican in nude protest for gay marriage. (VIDEO)

Two activists from the Ukrainian feminist group Femen were dragged away from the edge of Saint Peter's Square by police late on Tuesday as they protested against the Vatican's opposition to gay marriage.

The protesters set off pink flares chanting "Pope no more!" before they were restrained by officers and carried to a police station.

The protest came as cardinals from around the globe locked themselves inside the Sistine Chapel to choose a new leader for Catholics.