The cardinals began the heavily ritualised and secret process of choosing a new leader for the world's 1.4 billion Catholics on Wednesday, locked away in complete isolation from the world.

In the evening, black smoke billowed from a chimney on the roof of the chapel, signaling an inconclusive first ballot.

On Thursday, they were expected to begin voting from around 9 am, according to what the Vatican said ahead of the meeting.

White smoke would signal the election of a new Church leader to replace Francis, who died in April.

If the first vote on Thursday is decisive, the election could be announced as early as around 11 am.

If not, smoke signals would come later in the day.

No pope in modern times has been elected on the first attempt, so Wednesday's black smoke was widely expected.

But given recent history, a final result is possible from the second day, when up to four rounds of voting can take place.

The red-hatted "princes of the Church" are due to hold two votes in the morning session and two in the afternoon, continuing in coming days until one man has secured a majority of at least two-thirds.

A record 133 cardinals from 70 countries are involved in the ballot, up from 115 from 48 nations in the last conclave in 2013, growth that reflects efforts by Francis to extend the global reach of the Church.

--Reuters--