Italian police on Thursday said 12 African migrants had died after being thrown overboard by fellow passengers in the latest high-seas tragedy in the Mediterranean, as another 41 boat migrants were feared drowned in a separate incident. Police in the Sicilian port of Palermo said they had arrested 15 Muslim migrants suspected of attacking Christian passengers after a religious row on a boat headed for Italy, which is struggling to cope with a huge spike in illegal migrants arriving on its shores. The 12 victims were all Nigerians and Ghanaians while the 15 suspects came from Senegal, Mali and Ivory Coast. They were charged with "multiple aggravated murder motivated by religious hate," according to a police statement. Distraught survivors, who set off from Libya on Tuesday before being rescued by an Italian vessel on Wednesday, told a "dreadful" story of "forcefully resisting attempts to drown them, forming a veritable human chain in some cases," police said.

In another drama, 41 migrants were missing feared drowned on after their dinghy sank en route to Italy, the International Organization for Migration (IOM) said, mere days after 400 migrants are believed to have died in another shipwreck off the coast of Libya. The four survivors in Thursday's shipwreck, who came from Nigeria, Ghana and Niger, said their boat sank after setting sail from Libya with 45 people on board. Their vessel was spotted by a plane, which alerted the Italian coastguard, but by the time a navy ship arrived to help them only four passengers were found alive. The latest deaths bring the number of migrants killed while trying to cross the Mediterranean this year up to 900, the IOM said, up from 96 between January and April last year. The agency said some 10,000 people had been rescued off Italy since Friday alone, with recent good weather prompting a spike in the number of boat migrants attempting the risky crossing, many of them fleeing conflict and poverty in Africa and the Middle East. The flood of people trying to reach Italy in recent days has been "extraordinary", IOM's Giovanni Abbate told AFP in the Sicilian port of Augusta, where more new arrivals were disembarking. Driven by desperation and undertaking a perilous journey, he said it was not the first time disputes between migrants on packed boats had turned deadly, in reference to the 12 Christians allegedly thrown overboard. "Terrible tensions can arise, anything can happen," he said. The IOM in a statement said it had received reports of "a fight between different groups, maybe for religious reasons... on one of the boats rescued some days ago".

Nigerian and Ghanaian survivors told police a group of Muslim passengers on the boat, which was carrying around 100 people, began threatening the Nigerians and Ghanaians after they declared themselves to be Christians. "The threats then materialized and 12 people, all Nigerian and Ghanaian, are believed to have drowned in the Mediterranean," the police statement added. Italy pleaded for more help Thursday from other European Union countries to rescue the migrants and share the burden of accommodating them. Italy is not the final destination for most of those who risk their lives each year in search of a better life in Europe, but as their first port of call it is saddled with handling all asylum requests as well as saving those in danger from a watery grave. "Ninety percent of the cost of the patrol and sea rescue operations are falling on our shoulders, and we have not had an adequate response from the EU," Foreign Minister Paolo Gentiloni told the daily Corriere della Sera.

"Then there is the difficult issue of knowing where to send those rescued at sea -- to the nearest port? To the country where their boat came from? The EU has to respond clearly to these questions," Gentiloni said. The crisis is only expected to intensify, with the Red Cross predicting record numbers of boat migrants this year. "The flow is unstoppable, and we, the international community, are failing to deliver on our commitments," said Francesco Rocca, president of the Italian Red Cross. Amnesty International said it had been raising the alarm "for months" and urged European leaders to take action. "A season of death is now upon us," said Gauri van Gulik, the rights group's deputy Europe and Central Asia program director. "It is an appalling indictment of European governments' lack of compassion that so little has been done when so many people remain at risk of dying off Europe's southern shores."