Austria said on Friday 71 refugees, including a baby girl, were found dead in an abandoned freezer truck, while Libya recovered the bodies of 105 migrants washed ashore after their overcrowded boat sank on its way to Europe.
Almost 100 more were missing and feared dead.
Both tragedies were a result of a renewed surge in migrants fleeing war and poverty that has confronted Europe with its worst refugee crisis since World War Two.
The International Organization for Migration said it estimated a third of a million people had crossed the Mediterranean so far this year to wash up in southern Europe.
Almost two-thirds had arrived in Greece and most of the rest in Italy. At least 2,636 had perished in the attempt.
German Chancellor Angela Merkel said European Union leaders were ready for an emergency meeting, if necessary, to discuss the refugee crisis. The White House urged Europe to crack down on traffickers and ensure that migrants' human rights were protected.
In the latest disaster off the coast of North Africa, a vessel packed with an estimated 400 migrants sank on Thursday after leaving Zuwara in Libya. The port is a major launchpad for smugglers exploiting a security vacuum in a country with two rival governments.
Lacking navy ships, Libyan officials were searching for survivors with fishing boats and inflatables provided by locals. About 198 people had been rescued by noon, officials said.
"The boat was in a bad condition and people died with us," said Ayman Talaal, a Syrian survivor, standing next to his daughter. "We have been forced into this route. It's now called the grave of the Mediterranean Sea."
The migrants were from sub-Saharan Africa, Pakistan, Syria, Morocco and Bangladesh, a security official said. Many appeared to have been trapped in the hold when the boat capsized.
Local officials and residents were putting bodies into red bags on a beach littered with shoes, trousers and other personal items from drowned migrants.
STARVED OF AIR
Most migrant deaths have happened at sea. The gruesome find of a truckload of corpses in Austria highlighted the danger faced by those who make it across to southern Europe but depend on trafficking gangs to ship them north towards more affluent countries like Germany.
A motorway patrol discovered the abandoned lorry near the Hungarian border on Thursday, probably at least 24 hours after it had been parked there. The refugees appeared to have been dead for up to two days and fluids from the decomposing bodies were seeping from its door.
A Syrian travel document was found among the victims, but more time is needed to determine whether people of other nationalities were on board, Hans Peter Doskozil, police chief for the province of Burgenland, told a news conference.
The back door of the truck was not locked but secured shut with wires. Its refrigeration system showed no signs of having been switched on and there were no vents to allow fresh air inside, Doskozil told Reuters. The victims had been wearing light summer clothes.
Of the 71 dead, 59 were men, eight were women, and four were children, including a girl estimated at one to two years old and three boys aged roughly eight to 10.
Hungarian police said they had arrested four men – three Bulgarians and an Afghan – and had questioned roughly 20 people after conducting house searches.
"We expect that this is the trace that will lead us to the perpetrators," Doskozil said, making clear that the people being held were not the ringleaders of the trafficking gang.
Authorities were transporting the bodies to different Austrian morgues. A Reuters witness saw one truck carrying around 10 bodies entering a Vienna forensics centre.
Refugees and migrants have been sweeping north through the Balkans. Thousands of Syrians, Afghans and Pakistanis have crossed from Serbia into EU-member Hungary, where authorities said more than 140,000 had been caught entering the country so far this year.
Hungary, which is part of Europe’s passport-free Schengen zone, is building a fence along its border with Serbia to contain what it calls a threat to European security, prosperity and identity.
It plans to tighten laws next week to curb migration pressure on the country. That includes using the army, if necessary, to help police near the southern border, lawmaker Gergely Gulyas of the ruling Fidesz party said.
Hungarian police said 10 Syrian migrants were injured when a van driven by a Romanian suspected of human trafficking overturned en route for Budapest.
In Greece, coastguards said they had rescued more than 1,600 migrants making their way to Greek islands near Turkey over the past three days.
Police in Sicily detained 10 people on suspicion of multiple homicide and aiding illegal immigration after 52 migrants were found suffocated in the hull of a boat this week.
The U.N. refugee agency (UNHCR) said survivors said they had been beaten to force them into the hold, and then had to pay money to smugglers just to come out to breathe.
One of the survivors, an Iraqi orthopaedic surgeon, said he had paid 3,000 euros ($3,400) to come up on to the top deck with his wife and two-year-old son.
Last week, 49 people died in another boat's hold after inhaling poisonous fumes, and on Wednesday 21 people are thought to have died after a dinghy with 145 on board got into difficulty, UNHCR spokeswoman Melissa Fleming said.
