The International Organization for Migration (IOM) has warned that, based on current figures, the migrant death toll on the Mediterranean this year could top 30,000.
The IOM said late on Tuesday that it believed 1,727 migrants have died trying to make the journey to Europe from North Africa so far this year, compared to just 56 at the same time last year.
"IOM now fears that the 2014 total of 3,279 migrant deaths may be surpassed this year in a matter of weeks," the group said in a statement.
"We just want to make sure people understand how much more ... rapid these deaths have been coming this year," IOM spokesman Joel Millman said earlier on Tuesday.
The European Union proposed doubling the size of its Mediterranean search and rescue operations Monday, as the first bodies were brought ashore of at least 800 people feared killed in the deadliest known shipwreck of migrants trying to reach Europe.
The mass deaths on overloaded vessels making the journey from the north coast of Africa have caused shock in Europe, where a decision to scale back naval operations last year — after the rescue missions were viewed as encouraging migrants to make the dangerous journey — seems to have increased the risks for migrants without reducing their numbers.
Italian ships have rescued well over 10,000 people over the past two weeks, an unprecedented number for such a short period, authorities say. The rescues continued Tuesday, with another 112 migrants, all men, picked up in a deflating rubber life raft in waters some 50 miles north of the Libyan capital, Tripoli.
"The situation in the Mediterranean is dramatic. It cannot continue like this," said European Council President Donald Tusk, calling an extraordinary summit of EU leaders for Thursday to plan how to stop human traffickers and boost rescue efforts.
Malta's Prime Minister Joseph Muscat said as many as 900 people may have died in Sunday's disaster off the coast of Libya when a large boat capsized. That would be the highest death toll in recent times among migrants, who are trafficked in the tens of thousands in rickety vessels across the Mediterranean.
The number of refugees and migrants crossing the Mediterranean Sea has increased dramatically in the past year, according to rights group Save the Children. At least one-sixth of those who make the journey to Italy are children, and Syria continues to be the main country from which families are forced to flee, the group added.
The rights group accused EU leaders of "dithering" as children drown and prioritizing politics over human rights.
"What we needed from EU foreign ministers today was life-saving action, but they dithered. The emergency summit on Thursday is now a matter of life and death," Save the Children CEO Justin Forsyth said in a press release Monday.
EU ministers held a moment of silence at a meeting in Luxembourg to discuss the crisis. The bloc's executive, the European Commission, presented a 10-point plan to address the crisis, which would include doubling the size and the funding of "Triton," an EU naval operation in the Mediterranean.
But even that would leave the operation smaller and less well-funded than an Italian mission abandoned last year due to costs and domestic opposition to sea rescues.
As 27 survivors of the disaster arrived in Italy on a coast guard vessel late on Monday, authorities said the captain of the migrant boat and his deputy had been arrested on suspicion of people smuggling. According to survivors, hundreds of migrants were trapped in the boat's hold and went down with the ship.
On Tuesday, the United Nations High Commissioner for Refugees (UNHCR) said it believed the death toll was more than 800 people.
"From available information and the various accounts we've had, UNHCR now believes the number of fatalities to have been over 800, making this the deadliest incident in the Mediterranean that we have recorded," UNHCR spokesman Adrian Edwards said in Geneva.
Those who escaped with their lives described to officials the moment the trawler carrying them capsized after a Portuguese merchant ship approached the vessel, causing a stampede.
"There were a little over 800 people on board, including children aged between 10 and 12. There were Syrians, about 150 Eritreans, Somalians. ... They had left Tripoli at about 8 a.m. on Saturday," Sami said.
The survivors hailed from Mali, Gambia, Senegal, Somalia, Eritrea and Bangladesh, she added. Most were taken to nearby holding centers while one survivor was taken to hospital in Catania, on Sicily's east coast.
Italy and Malta were working to rescue another two boats carrying an estimated 400 people off the coast of Libya on Monday. Hundreds of miles to the east, coast guardsmen were struggling to save scores of migrants from another vessel destroyed after running aground off the Greek island of Rhodes.
The Greek coast guard said at least three people were killed there. Television pictures showed survivors clinging to floating debris while rescuers pulled them from the waves.
European officials are struggling to come up with a policy to respond more humanely to an exodus of migrants traveling by sea from Africa and Asia to Europe, but maintained they wanted to do so without encouraging more to leave.
"Search and rescue alone is not a silver bullet," said German Interior Minister Thomas de Maiziere. "If you just organize search and rescue, criminals who get the refugees on board will send more boats."
Nevertheless, Chancellor Angela Merkel said that alongside efforts to fight trafficking, more should be done to save those at sea: "We will do everything to prevent further victims from perishing in the most agonizing way on our doorstep."
The vessel overturned and sank off the coast of Libya on Sunday, apparently after passengers rushed to one side to attract attention from a passing merchant ship.
A Bangladeshi survivor told police there had been 950 passengers onboard, many locked into the hold and lower deck. However, Catania Chief Prosecutor Giovanni Salvi, who is conducting a homicide investigation into the case, said the figure needed to be treated with caution.
In the Maltese capital of Valletta, coast guard officers brought ashore 24 corpses found so far. Wearing white protective suits, they carried the victims in body bags off the Italian ship Gregoretti and deposited them in hearses as survivors looked on from the deck.
Twenty-seven survivors rescued so far arrived in the Sicilian port of Catania late on Monday. Another survivor was earlier taken to a Catania hospital by helicopter.
In Greece, more than 90 people were rescued from the boat wrecked off the coast of Rhodes: "We have recovered three bodies so far — that of a man, a woman and a child," a coast guard official said.
If the toll is confirmed in Sunday's tragedy, as many as 1,800 migrants will have died so far trying to cross the Mediterranean since the start of this year. In comparison, by the end of April 2014, fewer than 100 had died out of an estimated 26,000 who crossed.
The number of migrants normally surges in the summer, meaning far greater numbers are likely to attempt the voyage in the coming months. In total last year, 174,000 made the journey successfully and around 3,200 died.
"With each day we delay we lose more innocent lives and Europe slips further into an immoral abyss. Right now, people desperately seeking a better life are drowning in politics," Forsyth said in the release. "We have to restart the rescue — and now."
Al Jazeera and wire services