The mayor of the Italian island of Lampedusa warned European leaders gathered Thursday in a summit that they need an urgent rethink on immigration -- with Mediterranean and Balkan states demanding urgent EU action.

The little Mediterranean island has been swamped by an exodus from neighboring north Africa and hit the headlines this month when hundreds of African refugees and migrants drowned off its shores.

Italy on Monday was set to triple sea patrols amid a growing influx of asylum seekers making perilous crossings, as Prime Minister Enrico Letta said the Mediterranean should not be a "sea of death".

The plan is for a large-scale deployment of ships, planes, helicopters and reportedly even Predator drones in a show of force also intended to put further pressure on European states to help.

Divers on Saturday found an additional 20 bodies off the Italian island of Lampedusa, Italian media reported, bringing the still provisional death toll from an October 3 shipwreck to 359.

Only 155 of the about 545 migrants aboard the vessel, mainly from Eritrea, survived the disaster, the worst immigration tragedy for Italy in more than a decade.

Italian divers said the death toll from a refugee shipwreck last week had risen to 309 after seven bodies were recovered on Thursday and announced they had completed the search inside the wreck.

"There are no more bodies inside the wreckage. The search will continue in areas outside the wreckage," a coast guard official said.

Rescuers searched Friday for missing would-be migrants after plucking 54 people from the sea after their boat sank off the coast of the Italian island of Lampedusa overnight, rescue services said.

The Italian coastguards along with customs police and NATO ships were taking part in the search, the ANSA news agency reported.

Italian coast guards found 25 dead bodies in the engine room of a refugee boat fleeing Libya with 271 people crammed on board that arrived on the holiday island of Lampedusa Monday, port officials said.

"It's 25 bodies of men, presumed to be from sub-Saharan Africa," Antonio Morana, the commander of Lampedusa port, said on news channel SkyTG24.