“The coastguards have coordinated 15 rescue operations, some 2,000 migrants are safe and sound,” they said, adding that Italian navy vessels and ships from the EU's Frontex border agency and its Sophia military operation helped with the efforts.

More than 800 migrants were already rescued off Libya on Wednesday, mainly by vessels chartered by the aid groups Doctors Without Borders (MSF), SOS Mediterranee, MOAS and SeaWatch.

The United Nations' refugee agency estimates that over 48,000 migrants, most of them sub-Saharan Africans, have arrived in Italy since the start of the year in search of a better life in Europe.

A similar number made the treacherous sea journey over the same period last year.

But unlike previous years, new arrivals are increasingly finding themselves marooned in overcrowded camps in Italy as countries further north have shut their borders, effectively blocking their overland passage into the rest of Europe.

Charities such as MSF, Oxfam and Save the Children have expressed mounting concern over the dire living conditions for those stranded as a result of the bottlenecks – wich have also emerged along the Greek border.