As many as 500 migrants are feared to have drowned after traffickers reportedly rammed and sank their boat in what the International Organisation for Migration (IOM) described Monday as "the worst shipwreck in years".
Horrific details of the shipwreck, which occurred Wednesday near Malta, were told to IOM by survivors.
"If this story, which police are investigating, is true, it would be the worst shipwreck in years... not an accident but a mass murder, perpetrated by criminals without scruples or any respect for human life," IOM said in a statement.
Two surviving Palestinians plucked from the water by a freighter on Thursday told the IOM that around 500 passengers had been on one vessel which was wrecked on purpose by people smugglers.
According to the two, Syrian, Palestinian, Egyptian and Sudanese migrants set out from Damietta in Egypt on September 6, and were forced to change boats several times during the crossing towards Europe.
The traffickers, who were on a separate boat, then ordered them onto a smaller vessel, which many of the migrants feared was too small to hold them.
When they refused to cross over to the new boat, the furious traffickers rammed their boat until it capsized, the survivors told IOM.
"Two survivors brought to Sicily told us that there had been at least 500 people on board. Nine other survivors were rescued by Greek and Maltese ships, but all the rest appear to have perished," Flavio Di Giacomo, IOM's spokesman in Italy, told AFP.
The Maltese armed forces said seven people, all unconscious and suffering from hypothermia, were flown to a hospital on Crete.
They also said their initial information suggested a collision between a boat carrying up to 400 migrants and another carrying around 30.
- 'At any cost' -
Both Palestinians spent a day and a half in the water, one wearing a lifejacket and the other holding on to a life buoy with other migrants, all of whom perished.
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Among those who died was a young Egyptian boy who hoped to make money in Europe to pay for his father's heart operation, the IOM said.
This year has seen a surge in the numbers of migrants attempting to make the hazardous crossing from North Africa and the Middle East to Europe.
On Sunday, in a separate incident, dozens of African migrants were feared drowned after a boat carrying around 200 people sank off Libya, with only 36 survivors rescued.
According to the UN's refugee agency, UNHCR, over 2,500 people have drowned or gone missing attempting the crossing in 2014, including more than 2,200 since the start of June.
Hollywood star Angelina Jolie, a special envoy for the UNHCR, urged the international community to "wake up to the scale of the crisis".
"There is a direct link between the conflicts in Syria and elsewhere and the rise in deaths at sea in the Mediterranean," she was quoted as saying in a UNHCR statement on Monday.
"We have to understand what drives people to take the fearful step of risking their children's lives on crowded, unsafe vessels. It is the overwhelming desire to find refuge," she said.
"Unless we address the root causes of these conflicts the numbers of refugees dying or unable to find protection will continue to rise," she added.
Amnesty International insisted European leaders do more to provide safe and legal ways for refugees to get access to protection in the European Union.
"The response of EU member states to the refugee crises in the Middle East and North Africa has been shameful," John Dalhuisen, Amnesty International’s Europe and Central Asia Director, said in a statement.
He slammed European leaders for preventing people from reaching Europe "at any cost, forcing desperate people to take more hazardous routes".
The IOM also called on the international community to crack down on traffickers.
It said "the only way to render these organisations impotent is to begin to open legal canals into Europe for all those people, men, women and children, fleeing their homelands in search of shelter."
According to the Italian navy, some 2,380 migrants and asylum seekers were picked up over the weekend in a large-scale naval deployment dubbed "Mare Nostrum", launched after more than 400 people died in two shipwrecks last October.