WATCH | Body of Pope Francis taken to St Peter's before funeral

The body of Pope Francis is due to be moved to St Peter's Basilica on Wednesday to allow Catholic faithful to pay their last respects before a funeral expected to bring US President Donald Trump and dozens of other world leaders to Rome.

Francis, a groundbreaking reformer, died at 88 on Monday from a stroke and cardiac arrest, ending an often turbulent 12-year reign in which he repeatedly clashed with traditionalists and championed the poor and marginalised.

His body, lying in an open casket, was set to be taken from the chapel of the Vatican residence where he lived to St Peter's, entering through the central door, in a grand procession starting at 9am, with cardinals and Latin chants.

Long queues of people formed around the Vatican before the procession, which will be followed by a religious service in the basilica. The faithful and the public will then be allowed to visit the late pontiff until 7pm on Friday.

A funeral is scheduled for Saturday morning in St Peter's Square, due to be led by the dean of the college of cardinals, 91-year-old Giovanni Battista Re.

At least 200,000 people are expected to attend the outdoor service, the head of Italy's civil protection agency Fabio Ciciliano told the Corriere della Sera newspaper.

Trump, who clashed repeatedly with the pope on immigration, will be accompanied by first lady Melania. Leaders from Italy, France, Germany, Britain, Ukraine, EU institutions and Francis' home nation of Argentina also confirmed their presence.

Francis asked to be buried in St Mary Major, a Roman basilica he was particularly attached to, rather than St Peter's like many of his predecessors, with a simple inscription of his name in Latin, Franciscus.

On Tuesday the Vatican released images of the late pope dressed in his vestments, holding a rosary, with Swiss Guards standing beside his casket. Dignitaries, including Italian President Sergio Mattarella and Italian Jewish leaders, came to visit. His death, which came after he had appeared in public the previous day, still frail after a bout of double pneumonia and a five-week hospital stay that ended on March 23, set in motion ancient rituals.

About 60 cardinals had gathered on Tuesday to decide funeral plans, with more meetings due in the coming days on other urgent business.

The conclave, which will choose the new pope, is not expected to start before May 6. There is no clear front-runner to succeed Francis, though British bookmakers have singled out Luis Antonio Tagle, a reformer from the Philippines, and Pietro Parolin, from Italy, as early favourites.

In the meantime, in the period known as the sede vacante (vacant seat) for the global Catholic Church, a cardinal known as the camerlengo (chamberlain), Irish-American Kevin Farrell, is in charge of ordinary affairs.

Reuters