Pope Francis has denounced the "globalisation of indifference" that greets migrants who risk their lives trying to reach Europe.

He travelled to the farthest reaches of Italy to draw attention to their plight and to pray for those who never made it.

The tiny Sicilian island of Lampedusa, a treeless, strip of rock 9km long.

It is closer to Africa than the Italian mainland and is the main port of entry into Europe for African migrants smuggled by boat from Libya or Tunisia.

Francis decided last week to visit Lampedusa as his first pastoral visit outside of Rome.

It was spurred by a particularly deadly crossing in which a dozen migrants lost their lives.

Despite the spur-of-the-moment decision, the island came through, building a makeshift altar out of recycled wood from shipwrecked migrants boats.

Francis greeted newly arrived migrants, and during Mass on the island's sports field, thanked the residents for welcoming so many men and women over the years.

He prayed for those who died trying to make a better life for themselves and their families.

Dozens of Lampedusan fishing boats accompanied Francis's coast guard ship as it pulled into port, a seaborne motorcade to honour the first Pope to visit an island.

Lampedusa often complains that it has been forgotten by Europe as it processes the thousands of would-be immigrants who come ashore each year.

As his plane was landing, a boat carrying 162 Eritreans arrived in port.

This is the latest in a new wave of migrants taking advantage of calm seas and warm weather to make the treacherous crossing.

Francis, whose ancestors moved to Argentina from Italy, has a special place in his heart for refugees.

As archbishop of Buenos Aires, he denounced the exploitation of migrants as "slavery" and said those who did nothing to help them were complicit by their silence.

He repeated that message today, denouncing smugglers who take advantage of the poverty of migrants to enrich themselves.

While thanking the work of Lampedusans and volunteers who care for the newly arrived migrants, he challenged everyone to take responsibility for the migrants' desperation, urging them not to have "anesthesia of the heart".

He prayed that God forgives such indifference, and welcoming Muslim migrants in the crowd, wished them a good start of the holy month of Ramadan.

Francis has said he wants his to be a missionary church, one that goes to the "peripheries" to minister to the most marginal.

It was appropriate then that he choose Lampedusa as his first pastoral visit outside Rome, and its residents welcomed him warmly, shouting "Viva il Papa" and wildly waving the yellow and white flags of the Vatican.

As he pulled into port, Francis blessed a wreath of yellow and white flowers and tossed it into the sea in memory of those migrants who died.

He then disembarked and greeted a few dozen migrants one by one, stopping to chat with a few.

In yet another indication of how Francis is changing the rules of this papacy, he travelled by open-top vehicle through throngs of well-wishers.

He shunned the bullet-proof popemobile that popes usually use when outside the Vatican.

The Mass site was located near the "boat cemetery" that houses the remains of broken migrant ships that have reached Lampedusa's rocky shores.

According to the UN refugee agency, 8,400 migrants landed in Italy and Malta in the first six months of the year, almost double the 4,500 who arrived during the first half of 2012.

It is still a far cry from the tens of thousands who flooded to Italy during the Arab Spring exodus of 2011.

The UN High Commissioner for Refugees has recorded 40 deaths in the first half of 2013, and a total of 500 for all of 2012, based on interviews with survivors.

Fortress Europe, an Italian observatory that tracks migrant deaths reported by the media, says about 6,450 people died in the Canal of Sicily between 1994 and 2012.