More than 4,650 migrants were saved on Tuesday and 28 bodies recovered in more than 30 rescue missions off the Libyan coast, Italy's coast guard said on Wednesday.
This brings the total rescued in the last 48 hours to more than 10,000 refugees, and the death toll to 50 as people smugglers take advantage of relatively calm weather to push boats to sea.
The coast guard said the migrants on Tuesday were rescued from 33 boats, including 27 rubber dinghies.
At its closest, Libya is some 290 km (180 miles) from the Italian island of Lampedusa.
Some 13 ships from the coast guard, the Italian and Irish navies, private merchant vessels and humanitarian organisations were involved in the rescues. The coast guard gave no details about the deaths or about the nationalities of those saved.
The latest surge in new arrivals means at least 142,000 migrants have reached Italy since the start of the year and around 3,100 have died making the perilous trip. An estimated 154,000 came to Italy in 2015 and 2,892 died.
The vast majority come from Africa, including Nigeria, Eritrea, Guinea, Gambia, Sudan, Ivory Coast and Somalia.
The migrants are brought to Italy, where EU and Italian officials work together to identify and fingerprint the asylum seekers. European law says migrants must stay in the country where they first enter the bloc and Italy is increasingly struggling to deal with the growing numbers.