“Terrible news coming in of potentially large loss of life in a shipwreck off the coast of Libya,” Charlie Yaxley, a spokesman for UNHCR, said on Twitter on Tuesday.
“Around 60 people have been rescued and returned to shore. At least 40 people are estimated to be dead or missing.”
His comments came as Ayoub Gassim, a spokesman for Libya’s coastguard, told The Associated Press news agency that at least five bodies, including that of a child, were recovered near the western town of Khoms, about 120km east of the capital, Tripoli.
He said at least 65 people, mostly from Sudan, had been rescued and that search operations were under way for those still missing. The survivors also included people from Egypt, Morocco and Tunisia, according to Yaxley.
Alarm Phone, an independent support group for people crossing the Mediterranean Sea, said up to 100 people were on board the capsized vessel.
The group said it received a call from those on the boat, who “were in severe distress, crying and shouting, telling us that people had died already”.
Unseaworthy boats crammed with people undertaking the dangerous journey to Europe regularly capsize off Libya. Across the Mediterranean, more than 850 deaths have so far been recorded this year.
“These tragedies are preventable. Cannot accept large loss of life each month as normal,” Yaxley wrote on Twitter, calling for the return of European Union vessels in rescue efforts and for NGOs to be “free to save lives at sea”.
Libya became a major conduit for migrants and refugees fleeing to Europe after the uprising that toppled and killed longtime leader Muammar Gaddafi in 2011. Traffickers and armed groups have exploited Libya’s chaos since his overthrow.
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In recent years, the European Union has partnered with the coastguard and other Libyan forces to prevent people from making the sea journey to Europe.
Rights groups say those efforts have left people at the mercy of brutal armed groups or confined in squalid detention centres that lack adequate food and water.
Thousands of people are detained in centres in and around Tripoli, where eastern-based fighters loyal to renegade General Khalifa Haftar have been battling forces aligned with the country’s UN-recognised government since April.
Last month, an air raid on a detention centre housing migrants and refugees killed at least 44 people and wounded more than 130, according to the UN Support Mission in Libya.