European Union foreign ministers are set to meet in Luxembourg to discuss the growing crisis of refugee deaths in the Mediterranean after a smuggler’s boat sank off the Libyan coastline.
Officials say at least 700 people are feared dead after the boat capsized and sank in the Mediterranean Sea.
But Italian prosecutors, citing a survivor, say as many as 950 migrants could have been on board.
The Bangladeshi survivor told Italian authorities that hundreds of people had been locked in the hold of the vessel by the smugglers.
The tragedy takes the number of people killed among those seeking refuge in Europe from Libya and elsewhere to more than 1,500 this year alone.
The death toll has led to demands for a more coordinated European response to what Italian Prime Minister Matteo Renzi has described as a “plague in our continent”.
Britain’s Foreign Minister Philip Hammond will join his European counterparts in Luxembourg later today where leaders are expected to discuss the issue of people smugglers.
Responding to the latest tragedy, Mr Hammond said he was horrified by the death toll and the “vile trade” of smuggling.
He added that stopping the smuggling trade “demands a comprehensive, coordinated response” which targets traffickers.
A major search and rescue operation was launched by air and sea after the vessel went down about 120 miles south of the Italian island of Lampedusa on Sunday.
It is believed the vessel overturned when migrants moved to one side of the boat in a bid to get off and be rescued by an approaching merchant ship.
At least 28 people were pulled from the Mediterranean, while 24 people were confirmed dead.
General Antonino Iraso from the Italian Border Police said the sea in the area is too deep for divers, suggesting the final death toll may never be known.
Carlotta Sami, from the United Nations High Commissioner for Refugees, said: “It seems we are looking at the worst massacre ever seen in the Mediterranean.”
French President Francois Hollande said the EU must do more, adding that rescue and disaster prevention efforts need “more boats, more overflights and a much more intense battle against people trafficking”.
“Those who put people on these boats are smugglers,” he said.
“They are even terrorists, because they know perfectly well that these boats are unsafe and that they will destroy the boats in the middle of the sea and put hundreds of people at risk to their lives.”
Pope Francis also made a new appeal to EU leaders to act to stop the loss of life off Italy’s southern coast.
International aid groups and Italian authorities have criticised Europe’s so-called “Triton” border protection operation as inadequate.
It has a much smaller budget and narrower remit that the more comprehensive Italian search-and-rescue mission it replaced.
The “Mare Nostrum” or “Our Sea” operation was cancelled last year due to the cost.
Italy scaled back the mission after it was unable to persuade European partners to help meet its operating costs of €9m (£6.5m) per month.