Having saved some 3,680 people over the past three days, the coast guard said in a statement that a further 350 migrants, most believed to be minors, had been spotted on a boat off Sicily and an operation was under way to bring them ashore.

More than 16,000 people have made the dangerous crossing from north Africa to Italy in the first three months of 2016, some 6,000 more than in the same period last year.

The number of new arrivals is expected to climb further in coming months as warmer, more stable weather kicks in, making it easier for people traffickers to put to sea.

Italian officials have also warned that a deal to limit the number of migrants travelling via Turkey to Greece could increase the flows through Libya to Italy.

However, up until now, the vast majority of migrants using the Mediterranean route have continued to come from sub-Saharan Africa, with no significant increase in numbers of Syrians, Afghans or Iraqis, who have been using the Greek route.

Hundreds of thousands of migrants have reached Italy in recent years, looking for a better life in the West.

Most are believed to have moved swiftly on to wealthier northern Europe, taking advantage of the European Union's passport-free travel zone, but moves to suspend the border pact could make it much more difficult for them to leave.