Voting will begin Wednesday after the chapel is placed under a news blackout under pain of excommunication and will continue until one of the cardinals has won two-thirds support in a secret ballot. In the 20th and 21st centuries this has taken between two and five days.

Pope Francis died on April 21, triggering a call for the 133 cardinal electors to gather in the Sistine Chapel to select the new leader of the world's 1.4 billion Catholics.

With representatives from almost 70 countries across five continents, this conclave is the largest and the most international ever.

Tackling abuse

Some 80% of the cardinals were appointed by Francis, an energetic reformer from Buenos Aires who helped open up the Church during his 12-year papacy.

But experts warn against assuming they will choose a progressive like him, and many conservatives hope for someone who will turn the focus back onto traditional doctrine.

The 2,000-year-old Catholic Church has huge global influence but is struggling to adapt to the modern world and recover its reputation after the scandal of widespread child sex abuse by priests.

For the past fortnight, the cardinals have been holding near daily preparatory meetings to discuss the challenges - and what they want and need from their new leader.

In the final meeting before the conclave on Tuesday morning, they discussed Francis's reforms - on tackling abuse and on Vatican finances, among others, according to press spokesman Matteo Bruni.

They also discussed divisions within the Church and the need for a pope to bring hope, he said.

Francis dedicated many of his pronouncements to calling for peace around the world, notably in the Middle East and Ukraine.

In a statement, the cardinals noted "with regret" the lack of progress towards ending those conflicts, calling for ceasefires and negotiations without preconditions.

Five or six contenders

The cardinal electors - those aged under 80 - will gather for a mass on Wednesday morning ahead of the conclave, which begins at 4:30 pm (1430 GMT) that afternoon.

Both Francis and his predecessor, Benedict XVI, were elected within two days but the longest papal election in Church history lasted 1,006 days, from 1268 to 1271.

More than a dozen names are circulating as potential frontrunners, from Pierbattista Pizzaballa, the Latin Patriarch of Jerusalem, to Hungarian conservative Peter Erdo.

But bookmakers in London and Dublin were quoting odds suggesting Italian cardinal Pietro Parolin, the Vatican's chief diplomat, was the favourite at 5/2, followed by the Philippines' Luis Antonio Tagle at 3/1.

But with no candidate lists and no campaigning, and given the diversity of the electors, many experts warn that there could be a surprise.

Franco-Algerian cardinal Jean-Paul Vesco said the preparatory meetings - which include electors as well as older cardinals - have helped bring together a very disparate group.

"Finally, we have got to know each other," he told Italy's Corriere della Sera newspaper, adding that there are "at least five or six" contenders.

Living history

At the Vatican on Tuesday, tourists mulled over what they would like to see in the new pontiff.

"He must not be too closed-minded. He must support young people who have different values than us," said Mexican tourist Veronica de Garcia, 30.

But "a pope who is in favour of abortion is unthinkable, because there are things that cannot be negotiated", said Enzo Orsingher, 78, from Rome.

The cardinals are sworn to secrecy, risking excommunication if they reveal what happens in the conclave, and are forbidden from contacting the outside world until they have a decision.

The Vatican said it would cut the phone signal within the tiny city state from 3pm on Wednesday until a new pope is elected - although this will not affect St Peter's Square.

Required to leave their mobile telephones behind when the voting process begins, the cardinals will let the world know their progress by burning their ballots to produce smoke -- black for no decision, white for a new pope.

The staff who will support them during the election, from medics to lift operators, canteen and cleaning staff, are also bound to secrecy, and took their own oaths on Monday.

- AFP

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