POPE Leo XIV presided over his first mass as head of the Catholic church today, following his election by cardinals the evening before.

Previously known as Robert Prevost, the new pontiff is the first north American leader of the world's 1.4 billion Catholics.

In taking the papal name Leo and referring to some of more social justice-minded priorities of his immediate predecessor Francis, the Pope appeared to signal a strong line of continuity.

In his first address to the Catholic faithful from St Peter's Square on Thursday evening, the Pope said: "Together, we must try to find out how to be a missionary church, a church that builds bridges, establishes dialogue, that's always open to receive — like on this piazza with open arms — to be able to receive everybody that needs our charity, our presence, dialogue and love." 

Francis, the first Latin American pope, clearly had his eye on Mr Prevost and in many ways saw him as his heir apparent.

He sent him to Peru, where Mr Prevost had spent years as a missionary, in 2014 take over a complicated diocese in the south American country.

The then pope then brought him to the Vatican in 2023 to head the Vatican's powerful Dicastery for Bishops, which vets bishop nominations around the world.