A spokesman for the UN refugee agency says up to 150 refugees trying to reach Europe from Libya are believed to have died after their boat capsized in the Mediterranean Sea.
Charlie Yaxley, a spokesman for the Office of the United Nations High Commissioner for Refugees (UNHCR), said on Thursday that a further 150 survivors were picked up by local fishermen and then returned to the coast by Libyan coastguard.
It is not clear if the refugees were on one or two boats that left the Libyan town of al-Khoms, some 120km (74.5 miles) east of Tripoli.
If confirmed, the number of dead would be the highest for a shipwreck in the Mediterranean this year.
Thousands of refugees attempt to cross the Mediterranean to Europe every year, and Libya is a key departure point. The majority of refugees from Africa take the sea route from Libya to Italy to reach Europe, while some others depart from Morocco to Spain.
Most refugees are packed into flimsy inflatable boats that often break down or sink. UNHCR figures show about 164 people died on the route between Libya and Europe in the first four months of 2019.
The International Organization for Migration (IOM) said in May that 443 people had reportedly died on dangerous Mediterranean crossings so far this year, compared to 620 deaths for the same period in 2018.
Europe has faced its worst refugee crisis since World War II. The continent has been hit since 2014 by an unprecedented influx of refugees fleeing conflict-ridden zones in North Africa and the Middle East, in particular Syria.
But since mid-2017, the number of migrant journeys has declined dramatically. The decline is largely because Italy has engaged Libyan forces to stop refugees from setting off or return them to Libya if found at sea – a policy condemned by human rights groups and international organizations.
The rights groups say migrants who failed to make the crossing to Europe and sent back to Libya face hunger, beatings, torture, rapes and a lack of medical care.