Cardinals began a conclave under Michelangelo’s famous frescoes in the Sistine Chapel on Tuesday to elect a successor to Benedict XVI

Cardinals began a conclave under Michelangelo's famous frescoes in the Sistine Chapel on Tuesday to elect a successor to Benedict XVI, with the odds favoring another Western conservative as pope.

The 115 scarlet-robed cardinals filed into the chapel past liveried Swiss Guards, chanting the Latin hymn "Veni Creator Spiritus" ("Come Creator Spirit") to ask for divine guidance after Benedict's troubled eight-year papacy.

The "Princes of the Church" swore on the Bible never to reveal the secrets of their deliberations or face being cast out of the Church forever, before the doors of the chapel swung shut to indicate the beginning of the lock-in.

The cardinals -- who were all appointed by Benedict XVI or his predecessor John Paul II -- were set to hold a first round of voting later on Tuesday after which the ballots will be burnt in a special stove in the Sistine Chapel.

The smoke is famously turned white if there is a new pope but the Vatican has already said it expects the smoke from the burning of Tuesday's ballots to be black, indicating no pope has been elected.

From Wednesday, ballots will be burnt after two rounds of voting in the morning and two rounds in the afternoon -- with the eyes of the world focused on the color of the wisps of smoke emanating from a special chimney installed on the chapel's roof.

Modern-day conclaves normally last no more than a few days and a two-third majority is required.

The longest conclave in the past century -- in 1922 -- lasted five days. Benedict's election in 2005 following John Paul's death took just two days.