A quarter of a million faithful expected in St Peter's on Sunday.

More than 200 foreign official delegations are set to attend the inauguration Mass of Pope Leo XIV in the Vatican on Sunday morning.

The Mass will take place in St Peter's Square at 10.00, amid tight security in the Italian capital where around 6,000 police officers and 1,000 volunteers will be on duty.

Dozens of world leaders and heads of state will return to Rome, just over three weeks after many of them attended the funeral of Pope Francis.

Around a quarter of a million faithful are expected to attend the inauguration Mass of the Chicago-born pope following his election as leader of the world's 1.4 billion Catholics.

The US vice president JD Vance and secretary of state Marco Rubio, both Catholics, are expected to lead the US delegation.

Vance, who met Pope Francis the day before he died, has reportedly requested a one-to-one meeting with Leo XIV, the first pontiff in history from the US.

Italy will be represented by the highest offices of the state, including President Sergio Mattarella and prime minister Giorgia Meloni.

Also present will be French president Emmanuel Macron, British prime minister Keir Starmer, the new German Chancellor Friedrich Merz, and the president of the European Commission Ursula von der Leyen.

The new Canadian prime minister Mark Carney, Australian prime minister Anthony Albanese, Israeli president Isaac Herzog and Lebanese president Joseph Aoun will be in attendance.

Ukrainian president Volodymyr Zelensky has said he hopes to attend the event but his presence is not confirmed.

Buckingham Palace has announced that King Charles and his son Prince William (who attended the funeral of Pope Francis) will miss the pope's inauguration ceremony: they will be represented by Prince Edward, the youngest son of Elizabeth II and brother of the current sovereign.

Other royals expected at the Vatican on Sunday include Felipe and Letizia of Spain, Philippe and Mathilde of Belgium, and Albert and Charlene of Monaco.

For details of traffic restrictions and how to reach St Peter's Square by public transport on Sunday see the city website.

Photo credit: Fabrizio Maffei / Shutterstock.com.