Updated

The bodies of some 30 would-be migrants were found in the hold of a packed smugglers' boat making its way to Italy, the latest deaths in a surge of immigration to Europe, the Italian navy said Monday.

The boat was carrying nearly 600 people, and the remaining 566 survivors were rescued by the navy frigate Grecale and were headed to the port at Pozzallo, on the southern tip of Sicily. Overall during the weekend, the navy said it rescued more than 5,000 migrants, adding to the nearly 60,000 people who have made their way to Italy since the beginning of the year, compared with 42,000 in all of 2013.

Most are African or Middle Eastern refugees who pay hundreds or thousands of euros each to smugglers in Libya who pack them into unsafe fishing vessels for the crossing. Officials say the numbers have swelled this year due to the increasing instability in Libya.

The 30 corpses were discovered in the bow area of the boat during the rescue operation, according to a navy statement. The victims were believed to have suffocated or drowned during the crossing. Initial news reports said the migrants had suffocated because they were packed in so tightly. It wasn't clear if the boat was taking in water when it was rescued.

Italy beefed up its sea rescue operations last October after a migrant boat capsized off the Sicilian island of Lampedusa, killing more than 360 people. Italy has insisted that the European Union should shoulder more of the cost and burden of the rescue operations and says it will use its EU presidency starting Tuesday to press its case. Italy says it spends 9.5 million euro ($13 million) a month to operate the sea and air patrols.

The EU's home affairs commissioner, Cecilia Malmstrom, said in a statement Monday that the commission was preparing a plan to fight and dismantle the smuggling networks at their places of origin. She said the commission was making some 4 million euros ($5.45 million) available to Italy as emergency assistance to deal with the onslaught, though it was not clear if that is in addition to the 30 million euro in EU funds promised after the Lampedusa tragedy.