Il Nuovo Postiglione - First US pope as Robert Francis Prevost becomes Leo XIV

Tens of thousands of well-wishers cheered as Leo, successor to the late Pope Francis, appeared on the balcony of St Peter's Basilica to deliver the first address of his ministry.

"To all people, wherever they are, to all peoples, to the whole Earth, peace be with you," a smiling Leo told the crowd.

"Help us, and each other, to build bridges through dialogue, through encounter, to come together as one people, always in peace."

Leo's speech drew warm applause, especially a section where the prelate -- who spent many years in Peru -- broke into Spanish, and also when he paid tribute to his popular predecessor Francis, who died last month.

"We still keep in our ears that weak, but always courageous, voice of Pope Francis blessing Rome," he said, referring to the ailing Argentine's Easter Sunday address, a day before his death.

"We must seek together how to be a missionary Church, a Church that builds bridges, which hold dialogues, which is always open," he said.

- 'Great honour' -

The 69-year-old Prevost had been talked about as among the "papabili" -- cardinals thought qualified for the papacy -- and as someone who could defend and further Francis's legacy.

But he was not a globally-recognised figure among the Catholic rank and file.

World leaders raced to welcome his election as the 267th pope and promise to work with the Church on global issues at a time of great geopolitical uncertainty.

Leo, who spent years as a missionary in Peru, now faces a momentous task. As well as asserting his moral voice on a conflict-torn world stage, he must try to unite a divided Church and tackle burning issues such as the continued fall-out from the sexual abuse scandal.

As Cardinal Prevost, the new pope had defended the poor and underprivileged and had reposted articles online critical of US President Donald Trump's anti-migrant policies, but the White House chief nevertheless welcomed the election.

"Congratulations to Cardinal Robert Francis Prevost, who was just named pope," Trump said in a post on his social media platform.

"It is such an honour to realise that he is the first American Pope. What excitement, and what a Great Honor for our Country."

It was not known how many ballots it took to elect Leo XIV, but the conclave followed recent history in wrapping up in less than two days.

While the details of the election will forever remain secret, the new pope had to secure at least two-thirds of votes to be elected.

- 'Amazing' -

The crowds had swelled with emotion when white smoke billowed into the sky from the Sistine Chapel chimney Thursday, signalling an election on the cardinals' second day of voting.

The bells of St Peter's Basilica and churches across Rome rang out and crowds rushed towards the square to watch the balcony of the basilica, fitted out with red curtains for the first address from the new pope, who was introduced in Latin.

"It's an amazing feeling," said an elated Joseph Brian, a 39-year-old chef from Belfast in Northern Ireland, who came with his mother to Rome for the spectacle.

"I'm not an overly religious person but, being here with all these people just blew me away," he told AFP as people around him jumped up and down in excitement.

There were euphoric scenes as one priest sat on someone's shoulders waving a Brazilian flag and another lifted a heavy crucifix into the air in jubilation.

- 'Habemus Papam' -

"Habemus Papam, woooo!" howled Bruna Hodara, 41, from Brazil, echoing the words to be spoken on the balcony as the new pope is introduced.

She, like others, recorded the historic moment on her phone, as others waved flags and cried out "Viva Il Papa!" -- "Long live the pope!" in Italian.

"It's a once in a lifetime opportunity to be here to see the pope. It's really special... I'm excited!" said Florian Fried, a 15-year-old from Munich, Germany.

The papal inauguration usually takes place less than a week after the election with a mass celebrated before political and religious leaders from around the world.

Ahead of that, Leo will lead a mass Friday for cardinals in the Sistine Chapel and recite the Regina Caeli prayer in St Peter's Square on Sunday.

He will also hold an audience for the world's media on Monday.

Vatican spokesman Matteo Bruni told journalists Prevost's choice of papal name was "a clear reference to the social doctrine of the Church".

Francis died aged 88 after a 12-year papacy during which he sought to forge a more compassionate Church.

While he provoked anger from conservatives with his progressive approach, there had been many Catholics calling for a successor in his vein.

Some 80 percent of the cardinals who voted for Prevost were appointed by Francis.

With electors hailing from 70 countries around the world, it was the most international conclave ever.

I.Altadonna--INP