Roman Catholic cardinals will meet in a secret conclave to elect the new leader of the global Church starting from May 7, the Vatican has confirmed. 

The 16th-century Sistine Chapel, where conclaves are held, was closed to tourists on Monday to allow for preparations.

Cardinals under the age of 80 are eligible to vote for Pope Francis's successor, meaning some 135 from around the world are expected to participate in the highly secretive ballot. Francis, pope for 12 years, appointed nearly 80 per cent of the eligible cardinal electors.

A pope is elected when a candidate receives at least two-thirds of the eligible vote. Modern papal conclaves have stretched over more than one day and have involved multiple ballots.

Francis, who was buried after a funeral attended by world leaders and dignitaries on Saturday, was elected on the second day and on the fifth ballot of voting among Roman Catholic cardinals in 2013.

Since the 20th century, the longest conclaves were five days, for Pius X in 1903 and Pius XI in 1922. The later conclave saw 14 rounds of voting.

Francis, who died April 21 at age 88 after a series of health challenges, was the first pope elected from Latin America, and the first from the Jesuit order. 

There has never been a pope from North America, Asia, Oceania or Africa.

4 Canadian cardinals can vote

While Europe still has the largest share of cardinal electors, at about 39 per cent, that is down from 52 per cent in 2013, when Francis became pope. The second largest group of electors is from Asia and Oceania, with about 20 per cent.

Four Canadian cardinals are eligible to participate in the conclave: Thomas Collins, Michael Czerny, Francis Leo and Gérald Lacroix.

WATCH l World leaders, dignitaries gather to say goodbye to Pope Francis:

Pope Francis laid to rest at Santa Maria Maggiore basilica after funeral

Pope Francis was laid to rest Saturday at Santa Maria Maggiore basilica a a funeral mass at St. Peter’s Square attended by as many as a quarter million people. Francis died Monday at age 88 after suffering a stroke.

Marc Ouellet, who turns in 81 in June, is ineligible to vote but is not eliminated from consideration as the next and 267th pope. When the 2013 ballots were revealed, Ouellet had placed third in all five ballots, behind Italian cardinal Angelo Scola and Argentina's Jorge Mario Bergoglio, who chose the name Francis as pope in honour of St. Francis of Assisi. 

Many of the cardinals are little known outside their own countries and they will have a chance to get to know one another at meetings known as General Congregations that take place in the days before a conclave starts and where a profile of the qualities needed for the next pope will take shape.

Francis made a priority of appointing cardinals from places that had never had them, such as Myanmar, Haiti and Rwanda.

"We don't know each other," said Swedish cardinal Anders Arborelius, who will enter the conclave.