All eyes on the Vatican chimney as Cardinals search for a successor to Benedict XVI

Cardinals prepared for a second day of conclave behind the Vatican's walls to elect a pope on Wednesday, with all eyes on a chimney that will signal when there is a new leader for the world's 1.2 billion Catholics.

The 115 cardinals held a first inconclusive vote in the Sistine Chapel on Tuesday as they began the process of finding a successor to Benedict XVI, who brought a troubled eight-year papacy to an abrupt end by resigning last month.

Black smoke billowed into the night air above the Vatican, indicating that no-one had gained the two-thirds majority needed to become the 266th Roman pope.

White smoke -- produced by mixing the smoke from burning ballots with special flares -- would indicate that a new head of the Roman Catholic Church has been chosen.

As they awaited the outcome of the first vote, suspense mixed with hopes among the tens of thousands of pilgrims in St Peter's Square -- and in the Catholic Church worldwide, which is struggling in many parts with scandals, indifference and conflict.

Among the cardinals Italy's Angelo Scola, Brazil's Odilo Scherer and Canada's Marc Ouellet -- all conservatives like Benedict -- are the three favourites but there is no clear frontrunner and conclaves are notoriously difficult to predict.

Some analysts suggest that Benedict's dramatic act -- the first papal resignation in over 700 years -- could push the cardinals to take an equally unusual decision and that an outsider could emerge as a compromise candidate.

Hopes are high in the Philippines for the popular Archbishop of Manila, Luis Antonio Tagle, and on the African continent for South Africa's Wilfrid Napier, the archbishop of Durban, but in practice their chances are very slim.

Two-thirds of the cardinals are from Europe and North America and the view among many experts is that only someone with experience of its inner workings can reform the scandal-tainted Vatican bureaucracy, the Roman Curia.

The cardinals on Tuesday filed into the chapel, chanting a Latin hymn to ask for divine guidance and swearing a solemn oath never to reveal the secrets of their deliberations on pain of excommunication.

The "Princes of the Church" are cut off from any contact with the outside world for the duration of the conclave. They eat and sleep in a Vatican residence where windows are locked shut and phones are for internal use only.

Modern-day conclaves normally last no more than a few days. Benedict's election in 2005 following the death of John Paul II took just two days.

Dressed in their scarlet robes, traditionally symbolising the blood they are willing to spill in the service of the Church, the cardinals held a pre-conclave mass in St Peter's Basilica where they prayed for unity.

The cardinals burst into thunderous applause when the dean of the College of Cardinals, Angelo Sodano, in his homily thanked the "beloved and venerable" Benedict -- who has kept well away from the run-up to the conclave.

Pilgrims descended on Rome to attend what is usually an extremely rare landmark in the history of the Church and millions worldwide were following the smoke signals from the Vatican with religious devotion or simple curiosity.

"Without a pope I feel bereft, like an orphan," said French priest Guillaume Le Floch, 35.

"The Church needs a great leader now more than ever," he said.

What many cardinals want is a leader who can re-ignite Catholic faith -- particularly among young people -- in the way the charismatic John Paul II did.

At his last Sunday mass before the conclave, US Cardinal Sean O'Malley said the new pope should "make more visible the love of the Good Shepherd".

There have been calls too from within the Church for a rethink of some basic tenets such as priestly celibacy, the uniform ban on artificial contraception and even allowing women to be priests as in other Christian denominations.

The scandal of sexual abuse of children by paedophile priests going back decades -- and the cover-up of their actions by senior prelates -- also cast a long shadow on the Church that the next pope will inherit.

The tradition of holding conclaves -- literally "with key" in Latin -- dates back to 1268 when cardinals were locked into the papal palace in Viterbo near Rome by an angry crowd because they were taking too long to choose a pope.

Their conclave still dragged on for nearly three years, despite townspeople tearing off the roof of the palace and feeding them only bread and water.

The 85-year-old Benedict announced on February 11 that he no longer had the strength of body and mind to keep up with the modern world.

In a series of emotional farewells, the German-born pope said he would live "hidden from the world" and wanted only to be "a simple pilgrim".