Pope Francis arrived in Marseille on Friday for a two-day visit focused on the Mediterranean and migration, bringing to France a message of tolerance amid bitter debate over how Europe manages asylum seekers.

Marseille was decked out in the yellow and white colours of the Vatican for the first visit by a pope to France's second-largest city in 500 years, where 100,000 people are expected to turn out to see the pontiff in his "popemobile" on Saturday.

The 86-year-old is visiting to take part in a meeting of Mediterranean-area Catholic bishops and young people – but his trip comes at a politically sensitive time.

The pontiff disembarked at Marseille airport from his plane away from the view of cameras. He was then wheeled in a wheelchair towards Prime Minister Elisabeth Borne, who was waiting on the airport tarmac to greet him.

He then stood up from his wheelchair to acknowledge the welcome of a military band.

A surge in migrant boats arriving from North Africa on the tiny Italian island of Lampedusa last week trigged outrage in Italy and a heated debate across Europe over how to share responsibility for the numbers.

Marseille is a historic gateway for immigrants and also home to some of the poorest neighbourhoods in Europe, many of which are plagued by drug trafficking.

The desperate conditions that cause many people to leave their homes for a new life, and the risks they take to do so, have been a key theme during Francis's decade as head of the Catholic Church.

Speaking at the Vatican on Sunday, he noted that migration "represents a challenge that is not easy... but which must be faced together."

He emphasised the need for "fraternity, putting human dignity and real people, especially those most in need, in first place."

Ahead of what will be his 44th overseas trip, Francis acknowledged this month that papal voyages were not as easy as they used to be.

He underwent hernia surgery in June, less than two years after having colon surgery, and routinely uses a wheelchair because of a troublesome knee.

Despite the decline in France of Catholicism, the once dominant faith, the pope's visit has sparked huge enthusiasm, with almost 60,000 people expected at a mass on Saturday afternoon. (AFP)