About 4,500 migrants were rescued from rubber dinghies in the Mediterranean on Thursday, the Italian coastguard said, averting another potential high seas disaster.

A coastguard spokesman said it appeared many people had left the Libyan coast to attempt the perilous voyage across the sea to Europe during a spell of good weather.

"We saved a total of about 4,500 people in about 40 rescue operations," the spokesman told AFP, adding the operations were continuing and the number may rise.

A body was found on board one of the rubber dinghies, he added.

Most of the migrants were on the dinghies, while two wooden boats were being used by Libyan people traffickers, the coastguard said.

"We registered a large number of voyages today, after several days of bad weather at sea had stopped people leaving Libya," the spokesman added.

The Italian navy also noted a mass movement of boats in the Mediterranean from "the first light of dawn."

Five navy ships took part in the rescue operations, together with two vessels from the EU's Operation Sophia, which was set up to combat human smuggling in the Mediterranean, and another four from humanitarian organisations.

More than 10,000 people have died crossing the Mediterranean to Europe in overcrowded boats since 2014, according to UN figures published earlier this month.

This year alone more than 50,000 migrants and asylum seekers from Africa have managed to complete the journey to Italy, a country that, like Greece, acts mainly as a gateway to northern Europe for most of the newcomers.