A crowded fishing boat that one survivor said carried 700 migrantscapsized north of Libya overnight, and only a few dozen people were rescued Sunday, raising fears that it could become the Mediterranean's deadliest knownmigrant sea disaster.
The capsizing prompted more dismay among exasperated Italian officials, refugee aid officials agencies and Pope Francis, all of whom are demanding more European or international action to stop a deadly tide of migration.
Migrants have aimed for Europe's shores for many years, fleeing war, persecution and conflict in Africa, the Middle East and Asia. But the turmoil and warfare in Libya has made it easier for smugglers to take to the sea.
Rescuers Sunday were "checking who is alive and who is dead" among the bodies floating on the surface, said Maltese Prime Minister Joseph Muscat, whose tiny Mediterranean nation joined the rescue operations. He called it the "biggest human tragedy of the last few years."
The 20-meter (66-foot) vessel may have overturned because migrants rushed to one side of the craft late Saturday night when they saw an approaching Portuguese-flagged container ship, the King Jacob, which the Italian Coast Guard had dispatched to help them.
The Coast Guard said at least 28 survivors had been rescued by Sunday morning. Muscat put the number of survivors at 50, and International Organization for Migration spokesman Joel Millman said 49 survived.
"Since the waters of the Mediterranean Sea are not too cold at the moment, the authorities hope to find more survivors," a statement from Millman said.
The container ship received the Coast Guard's request to help the migrants at 11 p.m. (2100 GMT) Saturday night "when an overloaded fishing boat was spotted close by the King Jacob's port side," according to a statement from a spokesmen for the ship owner.
The crew "immediately deployed rescue boats, gangway, nets and life rings. Twenty-two people were pulled to safety" and transferred Sunday to Italian coast guard vessels, that statement said.
A United Nations refugee agency spokeswoman Carlotta Sami tweeted that according to one survivor, the boat had set out with 700 migrants aboard.
Italian Premier Matteo Renzi summoned his top ministers to a strategy session in Rome Sunday evening, saying that the numbers of dead are still provisional but "are destined to rise.'
"How can it be that we daily are witnessing a tragedy?" Renzi asked.
The smugglers are capitalizing on the migrants' desperation and taking advantage of chaos and violence in Libya, where rival militias, tribal factions and other political forces have destabilized the country since bloody end of the long dictatorship of Moammar Gadhafi in 2011.
In Italy's Parliament, the leaders of foreign affairs and defense commissions pushed for the EU and the UN to prepare a naval blockade of Libya's coast to stop the human trafficking.
Without a military blockade, "the traffickers will continue to operate and make money and the wretched will continue to die," said Pier Fernando Casini, the Senate foreign affairs commission president.
The pope lent his moral authority to the political calls for action, urging "the international community to act decisively and promptly, to prevent similar tragedies from occurring again."
Until this Sunday's tragedy, calls for a naval blockade had mainly risen in Italy from the anti-immigrant Northern League party. That top lawmakers are now joining the chorus reflects rising impatience for decisive European action.
"Europe can do more and Europe must do more," said Martin Schulz, president of the European Parliament. "It is a shame and a confession of failure how many countries run away from responsibility and how little money we provide for rescue missions."
The EU's foreign minister, Federica Mogherini, added migration as a last-minute emergency issue to an EU foreign ministers' meeting on Monday in Luxembourg.
Europe must mobilize "more ships, more overflights by aircraft," French President Francois Hollande told French TV Canal +. He said he called Renzi to discuss emergency action.
The prime minister of Spain, another Mediterranean nation, also urged Europe to take swift action.
"Today, and this is the umpteenth time, we hear of yet another human tragedy in the Mediterranean, off the Libyan coast," Mariano Rajoy told a political rally. "It's a daily drama. Three days ago it was 400 people. Four days ago they were 10. Words won't do any more."
There was no immediate way to determine how many were on board the fishing boat, nor how many might still be rescued, the Coast Guard and other authorities said. The total number of passengers was expected to be clarified as authorities interview survivors.
Given that the sea is as deep as 3 miles (5 kilometers) or more in the area, it is possible that many bodies will never be recovered, as was the case in similar tragedies off the coasts of Libya, Italy, and other Mediterranean nations in recent years.
"There are fears there could be hundreds of dead," Pope Francis told the faithful in St. Peter's Square on Sunday. He bowed his head in silent prayer, as did many of the tens of thousands below him.
When asked whether migrants rushed to one side as the Portuguese vessel pulled alongside, Italian Border Police Gen. Antonino Iraso replied: "The dynamics aren't clear. But this is not the first time that has happened."
Rescuers reported seeing wreckage in the sea.
"There are large fuel stains, pieces of wood, life jackets," added Iraso, whose force has boats deployed in the rescue effort, told Sky TG24 TV.
The numbers of migrants attempting the dangerous crossing from Libya in overcrowded or unseaworthy boats swells as the springtime weather improves, providing calmer seas and warmer water.
Even before this latest capsizing, more than 900 are known to have died in failed crossings this year. Last week, 400 people were presumed drowned when another boat capsized.
Since the start of 2014 and through this month, nearly 200,000 other migrants have been rescued at sea in operations conducted or coordinated by Italy and brought to Italian shores.
EU ministers to meet following tragedy
EU ministers are set to meet this week to discuss the way forward after the latest tragedy in the Mediterranean.
According to international media reports, the meeting is to be held following a request by French President François Hollande, who pointed out on Canal+ Television that "if confirmed, this would be the worst disaster in recent years in the Mediterranean."
The French President said that rescue and disaster prevention efforts will need "more boats, more over flights and a much more intense battle against people-trafficking," adding that he had phoned Italian Prime Minister Matteo Renzi in the wake of the tragedy.
Pope calls for action
Pope Francis appealed to the international community to take swift and decisive action to avoid more tragedies.
"They are men and women like us, our brothers seeking a better life, starving, persecuted, wounded, exploited, victims of war. They were looking for a better life," he told tens of thousands of people in St. Peter's Square for his Sunday noon address.
"Faced with such a tragedy, I express my most heartfelt pain and promise to remember the victims and their families in prayer," he said, departing from his prepared text.
"I make a heartfelt appeal to the international community to react decisively and quickly to see to it that such tragedies are not repeated," he said, before asking the crowd to pray "for these brothers and sisters".
'We have had too many never agains'
EU foreign policy chief Federica Mogherini also urged European governments to support action to protect migrants in the Mediterranean.
"We have said too many times 'never again'. Now is time for the European Union as such to tackle these tragedies without delay," Mogherini said in a statement. "We need to save human lives all together, as all together we need to protect our borders and to fight the trafficking of human beings."
President in strong appeal
President Marie-Louise Coleiro Preca said Malta could no longer look at migration as a "bogeyman" to be feared.
In an impassioned speech at the Vilhena Band Club in Floriana to mark the feast of St Publius, she called for society to welcome and show love to those who appeared as outsiders.
"We cannot have peace while people act in a hostile manner at others just because they see them with dark skin or wearing a headscarf," she said.
"There are no easy solutions to migration. It's no longer just about war. In today's world people are on the move, just like our own children are going abroad to better themselves. If it were us - if we had to leave home for a chance at life with human dignity - wouldn't we take that chance?"
UNHCR insists urgent action is needed
The UN High Commissioner for Refugees António Guterres expressed his shock at the tragedy, which appears to be the largest loss of life from any incident on the Mediterranean involving refugees and migrants.
"This disaster confirms how urgent it is to restore a robust rescue-at-sea operation and establish credible legal avenues to reach Europe. Otherwise people seeking safety will continue to perish at sea," Mr Guterres said
"But it also points to the need for a comprehensive European approach to address the root causes that drive so many people to this tragic end. I hope the EU will rise to the occasion, fully assuming a decisive role to prevent future such tragedies."
The UNHCR observed that it has been advocating for an urgent response from the EU to deal with the challenges faced by the thousands of people risking their lives to find safety in Europe. It has shared a comprehensive set of proposals, including a more robust search-and-rescue operation as well as credible legal avenue to reach safety - such as resettlement, humanitarian visas, and enhanced family reunification.
Amnesty decries avoidable 'man-made tragedy'
In a statement, Amnesty International said that the latest capsizing of a boat carrying refugees and migrants in the Mediterranean was "a man-made tragedy that could well have been avoided."
"What we are witnessing in the Mediterranean is a man-made tragedy of appalling proportions. These latest deaths at sea come as a shock, but not a surprise," Amnesty International director for Europe and Central Asia John Dalhuisen maintained.
"Whilst merchant vessels and their crews have bravely attempted to fill the gap left by the chronic shortfall in specialist search and rescue teams, they are not designed, equipped or trained for maritime rescue. It is time for European governments to face their responsibilities and urgently set up a multi-country concerted humanitarian operation to save lives at sea."
MOAS makes stark warning
Malta-based search and rescue charity Migrant Offshore Aid Station warned that thousands more people would perish in the coming weeks unless more assets are immediately deployed to the Mediterranean Sea.
"Every day we are waking up to news of more deaths in the Mediterranean. Scaling down Europe's rescue operations has not discouraged these desperate migrants from risking their lives in these dangerous crossings. It has only led to more deaths," MOAS director and former AFM commander Martin Xuereb said.
"We must take politics out of search and rescue. We must put saving lives at the top of the agenda. Meanwhile, society must not be a bystander. We must lead by example and show support to the search and rescue efforts being undertaken. The people making these crossings are people like us, with hopes and aspirations. They do not deserve to be left at sea to die," he added.
MOAS also announced that it will be redeploying its own rescue operation on May 2 - it had saved some 3,000 lives in 60 days last year. This year, it will be partnering with Doctors Without Borders, which will be taking care of the post-rescue care of any rescued migrants.
The charity is equipped with a 40-metre vessel, two Schiebel camcopters, two rescue RHIBs, and a 20-strong professional crew of seafarers, rescuers, doctors and paramedics, and is currently seeking funding to allow it to operate a year-long rescue operation.