Hundreds of people are feared to have drowned after a boat carrying up to 700 migrants capsized in the Mediterranean Sea, the Italian coastguard says.
A major rescue operation is under way after the vessel carrying "between 500 and 700 migrants" capsized at midnight local time, south of the Italian island of Lampedusa.
So far 28 people have been rescued.
Earlier this week,400 people were feared to have drowned when their vessel capsized north of Libya.
Maltese Prime Minister Joseph Muscat said that many people were feared dead.
Carlotta Sami, a spokeswoman for the UN's refugee agency, told Italian media: "At the moment, we fear that this is a tragedy of really vast proportions."
Italian ships, the Maltese Navy and commercial vessels are all involved in the rescue operation in Libyan waters, 210km off the coast of Lampedusa and 27km from the Libyan coast.
The Times of Malta newspaper reported that the migrants fell overboard when they rushed to draw the attention of a passing merchant ship.
Mark Micallef, a journalist with the paper, told the BBC such incidents were "not at all uncommon".
"We have seen this sort of scenario happen all over again, where a boat gets capsized right at the moment of rescue.
"This is part of the problem: merchant vessels... ill equipped to do rescues, [are] being tasked to do a job they're not designed for," he said.
The Italian coastguard's spokesman said the operation was still focused on search and rescue, "but in time it will be a search [for bodies] only."
Twenty ships and three helicopters were currently involved in the rescue, he added.
Those rescued, and bodies recovered, will be brought to the coastal city of Catania, Italian media report.
Last year a record 170,000 people fleeing poverty and conflict in Africa and the Middle East made the perilous crossing to Italy.
With improving weather conditions, the number of people making the crossing of at least 500km has surged. But vessels provided by people smugglers are often underpowered and overcrowded.
- BBC -