Six migrants drowned and 30 were reported missing off the coast of Tunisia on Thursday after their boat sank during a bid to reach Europe, authorities and the Red Crescent said.
Coastguard units rescued 34 passengers after the vessel sank off Zarzis near the Libyan border, Tunisian Defence Ministry spokesman Mohammed Zekri said.
Survivors said 70 people had been aboard, including Egyptians, Sudanese and a Moroccan, when the boat set off from Libya towards European shores.
A search and rescue operation is under way for the remaining passengers, Mr Zekri said.
The survivors were taken to a port in Ben Guerdane, Tunisian Red Crescent official Mongi Slim reported.
Both Tunisia and Libya have been serving as launch pads for migrants looking to reach Europe, especially in the chaos following the toppling of Libyan dictator Muammar Qaddafi in 2011.
The central Mediterranean route has become the world's deadliest migration trail, humanitarian groups say.
Departures surged rapidly in 2021, with almost 55,000 migrants reaching Italy in the first 10 months of the year compared with fewer than 30,000 the previous year, the Italian government said.
The Tunisian Forum for Economic and Social Rights says that over the first three quarters of last year, the coastguard intercepted 19,500 migrants during crossing attempts.
The UN refugee agency says at least 1,300 migrants have disappeared or drowned over the same period.
