Pope Francis on Sunday called for an end to the deadly trafficking of migrants, a week after a boat sank off southern Italy killing at least 70 people.

"May the traffickers of human beings be stopped, may they no longer be able to dispose of the lives of so many innocent people," the Argentine pontiff, a fervent defender of refugees urged at the close of  the Angelus prayer.

"May these journeys of hope never again turn into journeys of death, and may the clear waters of the Mediterranean no longer be bloodied by such dramatic incidents," the 86-year-old Pope added.

Visibly moved, the pope then paid his respects in silence for a few seconds before the crowd in St Peter's Square.

The death toll from the tragedy off the coast of Crotone, Calabria, last week included 15 minors. Rescue workers are still searching for other victims.

Three suspected people smugglers have been arrested, Italian media reported.

They are suspected of having charged between 5,000 and 8,000 euros to each migrant they had brought to Turkey three days earlier.

The boat, which was believed to have been carrying about 180 people, mostly from Afghanistan, Iran and Pakistan, broke up just offshore in stormy weather, after possibly hitting a sandbank.

Under-fire Italian Prime Minister Giorgia Meloni on Saturday rejected any government responsibility for the  shipwreck