The pontiff will be greeted by some two million young people from all over the world at the Roman Catholic World Youth Day festival in Rio de Janeiro.

The first Latin American Pope will also celebrate Mass on the famous Copacabana beach and visit shanty towns.

Some 22,000 security staff will be on duty during the visit of the Pope, who is not using his armoured Popemobile.

Ahead of his week-long trip, the 76-year-old Pope from Argentina called on his followers to join him spiritually on his journey through prayer.

The pontiff is due to arrive in Brazil - the world's most populous Catholic country - later on Monday, and huge crowds are expected to greet him at Rio airport.

The Vatican says it has full confidence in the ability of Brazilian security forces to protect the pontiff during his visit.

However, Pope Francis' direct style of communication, his desire for close proximity with his flock and his frequent rejection of protocol are creating some worry among the organisers of the visit, the BBC's David Willey in Rome reports.

In Rio, the security forces have set up several monitoring centres to keep a close eye on the Pope's every step.

The pontiff will also be using army helicopters to avoid Rio's heavy traffic jams.

The Brazilian authorities earlier banned masks at Pope Francis's opening Mass at the World Youth Day.

They are worried that the visit could spark a repeat of June's unrest, when many wore masks in the crowds.

There were widespread anti-government protests last month during the football Confederations Cup. Many of the protesters were wearing Guy Fawkes masks, which have become a feature of demonstrations around the world.

The demonstrators have taken to the streets to complain about the state of public services such as transport, health and education and about what they perceive as the inefficiency of their politicians.