VATICAN CITY, Holy See -- American Robert Francis Prevost's decision to choose Leo XIV as his papal name hints at the "social" brand he intends to give his pontificate, according to experts.

Once elected, a pope has only a short time to pick an official name before being ushered onto the balcony of St Peter's Basilica and presented to the world.

The choice usually reflects admiration for a previous pontiff.

It can signal continuity or a break with the past, and suggest whether the new leader of the Catholic church is progressive or traditionalist.

"The choice of name can be the first signal a new pope gives about the kind of pontificate he intends to have," Vatican expert John Allen said in a book on the conclave.

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

The previous Leo -- Leo XIII, who was pope between 1879 and 1903 -- was a determined defender of the rights of workers.

Leo XIII is best known for having denounced in an encyclical "the concentration in the hands of a few of industry and commerce... a small number of opulent men and plutocrats, who thus impose an almost servile yoke on the infinite multitude of proletarians".

He was "the pope of social teaching, with his 1891 encyclical 'Rerum novarum' which can be translated as 'of new things', there is an obvious social mark there," said Vatican expert and author Francois Mabille.

"At the time, in 1891, the issue was social justice, the workers' question," he said.

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Leo XIV's name choice suggests that "the theme will be taken up again, both in relation to the excesses of globalization, but also in relation to broader societal issues such as artificial intelligence".

The name could be interpreted as a tribute to his Argentine predecessor, Jorge Bergoglio, who in 2013 chose the papal name Francis in homage to Saint Francis of Assisi.

He was the first pope to pick Francis -- and in doing so defied the bookmakers, who had been betting the new pope would choose the name Leo.

© Agence France-Presse