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.

The conclave to select the next pope has begun after Catholic cardinals from across the world filed into the Sistine Chapel Wednesday before sealing themselves inside.

The 133 cardinals from 70 countries will be locked inside the Sistine Chapel, where they will vote in secret and silence, a process designed to be both contemplative and free from outside