At least 65 migrants drowned on Friday when their boat capsized in the Mediterranean Sea off the Tunisian coast after they had left Libya hoping to reach Europe, the UN refugee agency UNHCR said.
The state-run Tunis Afrique Presse agency gave a death toll of at least 70 people.
It is one of the deadliest shipwrecks involving migrants trying to reach Europe this year.
"This is a tragic and terrible reminder of the risks still faced by those who attempt to cross the Mediterranean," UNHCR Special Envoy for the Mediterranean Vincent Cochetel said in a statement.
In the first four months of 2019, 164 people are known to have died on the route, a smaller number but higher death rate than in previous years, with one dying for every three who reach European shores, UNHCR said.
The UN's International Organisation for Migration said on Friday the boat took to the sea from neighbouring Libya, where renewed warfare between rival factions has gripped the capital Tripoli in the past five weeks.
The boat sank 64km off the coast of Sfax, south of the capital Tunis, the Tunisian agency said. Fishing boats rescued the survivors.
The Tunisian Defence Ministry said the boat had left from the Libyan port of Zouara on Thursday aiming to reach Italy. Navy units have recovered only three bodies so far, it said in a statement.
"Another tragedy in the Mediterranean," the IOM said.
Libya's western coast is a main departure point for migrants from across Africa hoping to reach Europe by paying human traffickers, though numbers have dropped due to an Italian-led effort to disrupt smuggling networks and support the Libyan coast guard.
Migrants desembark from the Mare Jonio ship at the dock in the Italian island of Lampedusa island. Source: ANSA
Italy's Interior Minister Matteo Salvini let a charity boat carrying 30 rescued migrants dock at an Italian port but said the vessel would be impounded and not let out to sea again.
The migrants, including two pregnant women, a baby and four unaccompanied minors, were picked up by the Mare Jonio on Thursday off the coast of Libya as their rubber boat was sinking.
Earlier on Friday, UNHCR spokesman Babar Baloch said the United Nations had repeatedly voiced its concerns about the lack of boats to pick up migrants and refugees fleeing from "the horrendous and horrible situation" in Libya. It called on governments to step in.
