The Italian navy rescued 3,000 migrants aboard more than a dozen boats in the Mediterranean on Saturday after receiving requests for help from 22 vessels, the coast guard said.
Operations are continuing and it is still unclear where the people will be taken, a spokesman said.
Europe is struggling to cope with record influx of refugees as migrants flee war in Middle Eastern countries such as Syria.
The Mediterranean has become the world's most deadly crossing point for migrants. More than 2,300 people have died this year in attempts to reach Europe by boat, according to the International Organisation for Migration.
On Saturday, thousands of rain-soaked migrants stormed across Macedonia's border as police lobbed stun grenades and beat them with batons, seeking to enforce a decree to stem their flow through the Balkans to western Europe.
