The conclave to elect a new pope has officially begun, with a Vatican official calling out ''extra omnes'' and the door to the Sistine Chapel shutting.

Black smoke poured out of the Sistine Chapel chimney on Wednesday, signalling that no pope had been elected as 133 cardinals opened the secretive, centuries-old ritual to choose a new leader of the Catholic Church.

With all the pomp, drama and solemnity that the Catholic Church can muster, 133 cardinals began the centuries-old ritual to elect a successor to Pope Francis.