The ANSA news agency cited accounts from survivors of the shipwreck, who told rescuers they were on a boat that had set off from Sfax in Tunisia, which sank on its way to Italy.

However, they said the boat they were on capsized and sank after only a few hours.

The survivors, three men and a woman from Ivory Coast and Guinea, added they were rescued by a cargo ship and transferred to an Italian coast guard boat.

It comes only days after two boats capsized in the same area, prompting a rescue operation of more than 55 people.

It is not clear if the incidents are linked.

And then on Sunday, another 11 bodies were recovered from a shipwreck near Sfax, with more than 40 people still missing from that boat.

More than 93,000 migrants have arrived in Italy so far this year, compared to 44,700 in the same period a year before, the country's interior ministry said.