The Tunisian navy on Friday rescued 70 migrants from sub-Saharan Africa on a sinking rubber boat headed to Italy from Libya, the defence ministry said.

Ministry spokesman Mohamed Zekri told AFP the boat had broken down in international waters and was taking on water when the navy intervened at around 1:00 am local time.

Five women and four children, including a months-old infant, were among those on board, said Mongi Slim of the Red Crescent.

The migrants, who had set off Wednesday from western Libya, were taken to Zarzis port, near the Libyan border in southern Tunisia.

They were to undergo tests for COVID-19 and be confined to a Red Crescent centre, Slim said.

Nearly half of the 11,000 or so migrants who made shore in Italy this year set off from Tunisia, and most of those were Tunisian citizens, according to Rome.

Other arrivals largely set off from war-torn Libya.