Conclave to begin in the Sistine Chapel on 7 May.

Rome police authorities have drawn up a security plan ahead of the conclave when 133 cardinals will convene in the Vatican to elect a successor to Pope Francis.

Checkpoints will be set up in streets around St Peter's Square from 07.00 on Wednesday morning as pilgrims and the faithful flock towards the Vatican.

Security chiefs said the plan will be "open to modification" and would remain in place until the first official celebration by the new pontiff.

There will also be extra security measures at papal basilicas in Rome, in particular Santa Maria Maggiore or St Mary Major's where Pope Francis is buried.

The conclave will begin on Wednesday when the 133 cardinal-electors gather in the Sistine Chapel to take part in the highly secretive process to elect the 267th pope.

Vatican officials involved in the conclave were obliged to take an oath of secrecy, under penalty of excommunication, in a solemn ceremony that took place in the Pauline Chapel on Monday.

For the duration of the conclave, the cardinal-electors will reside in the Casa Santa Marta guest house in Vatican City, the former residence of Pope Francis.

The cardinals will also be sworn to secrecy and will be banned from communicating with the outside world. This means no phones, newspapers, television or internet.

To ensure there is no external contact or outside influence, the Vatican will use jammers to disrupt phone signals for the duration of the conclave.

Cardinals will vote a maximum of four times per day - twice in the morning and twice in the afternoon - until one candidate secures a two-thirds majority.

The new pope will need the backing of at least 89 cardinals to be elected.

As part of an ancient custom, the cardinals will use smoke from a chimney installed in the Sistine Chapel to signal to the world whether the round of voting has been decisive or not.

If the vote is inconclusive the smoke will be black. If a pope has been elected, the smoke will be white and the Vatican's bells will ring out.

Photo credit: Gennaro Leonardi / Shutterstock.com.