A boat carrying at least 47 migrants capsized in the Mediterranean on Sunday, the Italian coastguard warned.

The incident occurred during a rescue operation carried out with a freighter.

“During rescue operations [realizada] by motor boat […] the ship capsized during the transfer of migrants: 17 people were rescued by the ship and about 30 migrants are missing,” the coastguard said.

The ship had been reported Saturday night and strong waves hit the ship, despite merchant ships trying to protect it.

Last Saturday, more than 1,300 migrants were rescued by the Italian coastguard and navy when they were in overloaded boats in the Mediterranean Sea, less than two weeks after a shipwreck off the coast of southern Italy that left more than 70 dead, authorities said.

On Friday, several boats were deployed to assist three ships carrying hundreds of migrants in the central Mediterranean, the most dangerous migration route in the world.

According to rescuers, 487 of them were brought safely to the port of Crotona in the early hours of Saturday. Coast Guard videos released on Friday showed some of the migrants on the deck of a large fishing boat in rough seas.

Another operation, which rescued 500 migrants, was nearing completion, the same source said. The Ansa news agency reported that the boat, in which 584 migrants were traveling, had docked in the port of Reggio Calabria, a coastal town in southern Italy.

A third boat carrying 379 people was rescued by two Coast Guard patrol boats and the migrants transferred to a naval vessel bound for the Sicilian port of Augusta.