Italy's maritime search and rescue service have saved 3,500 migrants and found 19 corpses in the Mediterranean Sea since Friday.
Thousands have attempted to cross to Europe by boat over the weekend, the Italian navy said.
Calmer summer seas have led more people to make the perilous crossing this year from North Africa.
The breakdown of order in Libya has been exploited by human traffickers, pushing the number of arrivals into Italy since January past 100,000.
The Italian ship Sirio recovered 18 corpses and 73 survivors from a raft, the navy said on Twitter.
A frigate picked up one corpse along with 1372 survivors on Friday night.
The deaths were reported shortly after a boat carrying up to 200 migrants sank one kilometre from the Libyan coast on Friday, with most of its passengers feared drowned.
The Mare Nostrum search and rescue mission began after a shipwreck near Italy's coast killed 366 people last October.
The mission costs around €9m a month and has sparked fierce debate in Italy, which slipped back into recession in the second quarter after years of stagnation.
At the frontier between Europe and Africa, Italy has long attracted seaborne migrants, but the number of arrivals this year is already above a previous record of just over 60,000 for all of 2011, when the Arab Spring uprisings fuelled migration.
Italian Prime Minister Matteo Renzi has called on the European Union to take responsibility for rescuing migrants by investing in border control agency Frontex, and on the United Nations to intervene in Libya to manage the flows of refugees.