At least 150 people - including Pakistani and Bangladeshi nationals - drowned and many others were still missing, when a boat capsized off the coast of Tunisia, the UN has said.
Citing a report from the UN refugee agency, associate spokesperson Vannina Maestracci said this appeared to be "one of the worst and deadliest incidents in the Mediterranean so far this year", Xinhua reported.
"The overcrowded boat was carrying some 850 people, most from West Africa, Pakistan and Bangladesh. It left the Libyan capital and was headed for the Italian island of Lampedusa," she said.
The vessel left Tripoli on the afternoon of May 28, said a spokesman from the office of the UN high commissioner for refugees (UNHCR) in Geneva on Friday.
Maestracci added, "According to the survivors, the vessel was manned by people with little or no maritime experience, and by the third day, the passengers had run out of food and water."
A rescue operation by the Tunisian navy and coast guard is still in progress, she said.