A total of 741 migrants travelling in six boats have been rescued off Sicily, the Italian coastguard says.
The migrants, who had set sail from Libya, were picked up by EU naval vessels on Thursday, a coastguard spokesman told AFP news agency.
Last month the EU pledged to beef up maritime patrols and fight trafficking.
The UN estimates that 60,000 people have already tried to cross the Mediterranean in the past five months, and that about 1,800 people have died.
The death toll represents a 30-fold increase on the same period in 2014, according to the International Organization for Migration (IOM).
The rise has been attributed to chaos in Libya – the staging post for most crossings – as well as milder weather.
Many migrants are trying to escape conflict or poverty in countries such as Syria, Eritrea, Nigeria and Somalia.