About 6,055 migrants were rescued and 22 found dead on the perilous sea route from Africa to Europe on Monday, one of the highest numbers in a single day, Italian and Libyan officials said.
Italy's coastguard said at least nine migrants had died and a pregnant woman and a child had been taken by helicopter to a hospital on the Italian island of Lampedusa, halfway between Sicily and the Libyan coast.
Libyan officials said 11 migrant bodies had washed up on a beach east of the capital, Tripoli, and another two migrants had died when a boat sank off the western city of Sabratha.
One Italian coast guard ship rescued about 725 migrants on a single rubber boat, one of some 20 rescue operations during the day.
About 10 ships from the coast guard, the navy and humanitarian organisations were involved in the rescues, most of which took place some 30 miles off the coast of Libya.
Libyan naval and coastguard patrols intercepted three separate boats carrying more than 450 migrants, officials said.
Monday was the third anniversary of the sinking of a migrant boat off the Italian island of Lampedusa in which 386 people died.
According to the International Organisation for Migration, around 132,000 migrants have arrived in Italy since the start of the year and 3,054 have died.
Most depart from Libya, where political chaos and a security vacuum have allowed people smugglers to act with impunity.