The series of shipwrecks in the Mediterranean Sea over the past few days raises concerns that Europe is facing yet another summer with an overwhelming surge of new arrivals.

More than 700 migrants and asylum seekers likely died last week, aid and refugee agencies said today, most of them attempting to flee the Libyan coast for Italy in the deadliest period of migration to Europe this year.

Though the migrant influx tends to slow during the winter and early spring, waters are now growing warmer and calmer: Over the last week alone, 15,000 people arrived in Italy, many of them pulled to shore in dramatic emergency naval or coast guard rescue operations.

"This is the beginning of the peak season," Federico Fossi, a spokesman for the United Nations' refugee agency, said from Rome. "It's intense."


Fossi cautioned that the death toll from last week was an estimate based on accounts from survivors. But he said that in the span of three days starting last Thursday, there were three separate and deadly shipwrecks about 35 nautical miles from Libya. Photos from one rescue showed a trawler flipping over, shovelling hundreds of people into the sea. The week was likely the deadliest in the Mediterranean since April 2015.

Of last week's shipwrecks, the most catastrophic occurred on an engineless vessel tied to a fishing boat by rope. Some 500 migrants were on the fishing boat; 600 more on the vessel under tow were being dragged behind, Fossi said. When it began to sink, several dozen were rescued or managed to climb aboard the other boat. But 550 died or were left missing.

According to several accounts from news wire services, a Sudanese captain ordered the cutting of the rope between the two vessels as the latter began to take on water. That captain was arrested after his arrival in Pozzallo, a port town in Sicily.

"And let me tell you - this is quite a new thing," Fossi said. "We have never seen that before - a boat without an engine tied by a rope to the other one. That shows you the human traffickers are becoming really really greedy and cynical and merciless. Tying a boat to another one is really dangerous."

1 War, repression and government collapse in parts of the Middle East and Africa has caused the worst migration crisis since World War II.
2 In 2015, more than one million asylum seekers and migrants tried to enter European Union countries.
3 This year, nearly 200,000 have arrived on Europe's shores.
4 The influx has tested the continent's ability to cope and while provided fertile ground for politicians favoring tighter border control and decreased European integration.
5 Hungary has built razor wire fences along its borders with Serbia and Croatia. Austria narrowly defeated in a presidential race a right-winger vowing to "stop the invasion of Muslims."

Though a massive exodus from Syria is partly responsible for the unparallelled flow, the routes between Libya and Italy have tended to transport Africans - particularly Nigerians, Eritreans and Somalis.

Aid workers have speculated that Italy, rather than Greece, could emerge this year as the primary starting point for migrants following the closure of all borders between Greece and its northern neighbours.

That has effectively thwarted migrants from moving into the more prosperous parts of northern Europe.