Cardinals today moved into the Vatican as the suspense mounted ahead of a secret papal election with no clear frontrunner to steer the Catholic world through troubled waters after Benedict XVI's historic resignation.

The 115 cardinal electors who pick the next leader of 1.2 billion Catholics in a conclave in the Sistine Chapel will live inside the Vatican walls completely cut off from the outside world until they have made their choice.

In a series of centuries-old rituals today, cardinals will be sworn in with a solemn oath that threatens anyone who reveals the deliberations of the conclave with instant excommunication.