migrants
A migrant is helped as he disembarks from a Coast Guard boat in the Sicilian harbour of Palermo April 18, 2015. Reuters/Guglielmo Mangiapane

PALERMO, Italy (Reuters) - As many as 700 people were feared dead after a fishing boat packed with migrants capsized off the Libyan coast overnight in what officials said may be the Mediterranean's worst disaster as thousands flee poverty and war to Europe.

Top officials in Europe, whose recently-downsized border protection program has been criticized by international aid groups, said urgent action was needed. EU foreign policy chief Federica Mogherini said foreign ministers would discuss the issue at a meeting in Luxembourg on Monday.

If confirmed, the death toll would bring to 1,500 the total number of dead since the beginning of the year resulting from the flow of migrants seeking to flee insecurity in sub-Saharan Africa and the Middle East.

Only last week, around 400 migrants were reported to have died attempting to reach Italy from Libya when their boat capsized.

On Sunday twenty eight people were rescued and 24 bodies recovered from the 20 meter-long vessel, which sank around 70 miles from the Libyan coast, south of the southern Italian island of Lampedusa, the Italian coast guard said.

The United Nations High Commission for Refugees (UNHCR) said later that around 50 people had been rescued of the 700 reported to be on board.

"They are literally trying to find people alive among the dead floating in the water," Maltese Prime Minister Joseph Muscat said.

French President Francois Hollande said the EU had to do more, telling Canal+ television that rescue and disaster prevention efforts needed "more boats, more over flights and a much more intense battle against people trafficking."

"More EU countries must take responsibility for the refugee situation," said Sweden's Minister for Justice and migration Morgan Johansson, who called for an expansion of the EU's Triton border protection program, which only operates within 30 miles of the Italian coast.

The previous search and rescue operation "Mare Nostrum" was canceled last year because of the cost and because some politicians said it encouraged migrants to depart by raising their hopes of being rescued.

"This disaster confirms how urgent it is to restore a robust rescue-at-sea operation and establish credible legal avenues to reach Europe," said UNHCR head Antonio Guterres.

Italian Prime Minister Matteo Renzi called for an emergency meeting of European Union leaders this week, saying "We cannot remain insensitive when every day there is a massacre in the Mediterranean.".

The German government's representative for migration, refugees and integration, Aydan Ozoguz, said that with more arrivals likely to arrive as the weather turned warmer, emergency rescue missions should be restored.

"It was an illusion to think that cutting off Mare Nostrum would prevent people from attempting this dangerous voyage across the Mediterranean," she said.

"Looking For A Better Life"

Italian officials said 17 vessels from the navy and coast guard, merchant ships in the area and a Maltese patrol boat, as well as aircraft from the navy and coast guard, were involved in the search-and-rescue operation, which was being coordinated by the Italian coast guard in Rome.

There was still no decision on where the survivors and the bodies that had been recovered would be taken.

The boat is believed to have capsized when the migrants shifted to one side of the overcrowded vessel as a merchant ship approached.

"The first details came from one of the survivors who spoke English and who said that at least 700 people, if not more, were on board. The boat capsized because people moved to one side when another vessel that they hoped would rescue them approached," said Carlotta Sami, a UNHCR spokeswoman.

Pope Francis, who has spoken out repeatedly on the migrant crisis, repeated his call for quick and decisive action from the international community.

"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, they were looking for happiness," he told tens of thousands of people in St. Peter's Square for his Sunday noon address.

Aid groups have called for the opening of a "humanitarian corridor" to ensure the safety of the migrants but in Italy there were also calls to stop the boats from leaving and even to destroy them.

The leader of the anti-immigrant Northern League party, Matteo Salvini, called for an immediate naval blockade of the coast of Libya while Daniela Santanche, a prominent member of Silvio Berlusconi's Forza Italia party said Italy's navy must "sink all the boats."

Libya's lawless state, following the toppling of former leader Muammar Gaddafi in 2011, has left criminal gangs of migrant smugglers free to send a stream of boats carrying desperate migrants from Africa and the Middle East.

Around 20,000 migrants have reached the Italian coast this year, the International Organization for Migration (IOM) estimates. That is fewer than in the first four months of last year, but the number of deaths has risen almost nine-fold.

"A tragedy is unfolding in the Mediterranean, and if the EU and the world continue to close their eyes, it will be judged in the harshest terms as it was judged in the past when it closed its eyes to genocides when the comfortable did nothing," Maltese Prime Minister Joseph Muscat said.