Thousands of migrants in Italy are expected to turn up at St Peter's Square next Sunday to listen to the weekly address by Pope Francis before a special Mass for migrants in the basilica in Rome.

Pope Francis has personally chosen the theme of the Catholic Church's official "Migrants and Refugees Day" on January 17 as: "Migrants and refugees challenge us. The answer is the Gospel of mercy."

Italy's Migrantes Foundation will tomorrow announce the final plans for the event, taking place as part of the Pope's current Jubilee Year of Mercy.

Pilgrims at next Sunday's events will carry a cross made from the wood of wrecked migrant boats on the Italian island of Lampedusa, which has seen some of the worst sinkings and deaths in the crisis. Communion wafers for the Mass, to be celebrated by Cardinal Antonio Vegliò, President of the Pontifical Council for the Pastoral Care of Migrants and Itinerants, have been made by three prisoners serving sentences for murder in a high-security prison near Milan.

"These hosts, made by hands that have killed, bear witness that the need to be saved by the love of Christ touches every man and not only those serving a prison sentence," said spokesman for the Migrantes Foundation.