Cardinal Robert Prevost, a little known missionary from Chicago, was elected in a surprise choice to be the new leader of the Catholic Church yesterday, becoming the first US pope and taking the name Leo XIV.

Pope Leo appeared on the central balcony of St Peter's Basilica after white smoke had billowed from a chimney atop the Sistine Chapel signifying the 133 cardinal electors had chosen a new leader for the 1.4 billion-member Catholic Church.

"Peace be with you all," he told the cheering crowd, speaking in fluent Italian. He also spoke in Spanish during his brief address but did not say anything in English.

Prevost, 69, and originally from Chicago, has spent most of his career as a missionary in Peru and has dual Peruvian nationality. He became a cardinal only in 2023. He has given few media interviews and rarely speaks in public.

President Donald Trump swiftly congratulated Prevost on becoming the first US pope. "What excitement, and what a Great Honor for our Country. I look forward to meeting Pope Leo XIV. It will be a very meaningful moment!"

Prevost becomes the 267th Catholic pope after the death last month of Pope Francis, who was the first Latin American pope and had led the Church for 12 years.

Leo thanked Francis in his speech and repeated his predecessor's call for a Church that is engaged with the modern world and "is always looking for peace, charity and being close to people, especially those who are suffering".

He had not been seen as a frontrunner and there was a brief moment of silence when his name was announced to the packed St. Peter's Square, before people started to clap and cheer.

"I'm just thrilled. I hope this can bring to America a more loving community. I think there's a lot of hate in America. I think there's a lot of racism. I have experienced it," said Lailah Brown, 28, from Seattle, Washington, an African American.

"I hope America does not embarrass the pope," he said.