ROME - Rescuers plucked more than a thousand migrants from overcrowded boats near Libya on Wednesday morning, Italy's coast guard said, the most reported saved in a single day in three weeks.

The flow of migrants crossing the Mediterranean in rickety boats from Libya towards Italy's southern tip had been abating with deteriorating weather conditions and as more people chose alternative routes into Europe.

About 140,000 have reached Italy this year in boats from Africa out of a total of about 700,000 who have come to Europe by sea, mostly through Greece.

British, Irish, Slovenian and German navy ships took part in Wednesday's rescues along with the Italian coast guard and a ship operating under the auspices of European Union border agency Frontex.

Italy and Greece have struggled to cope with arrivals as civil war in Syria and deprivation and human rights abuses in Africa has driven the biggest wave of migration towards Europe since World War Two.