The Italian Coast Guard recovered the bodies of nine people and rescued 144 others after an Italy-bound boat sank 80 miles off the coast of Libya.
The Coast Guard confirmed on Monday that its members were deployed in the area in search for other missing people, Efe news agency reported.
Survivors and the remains of the deceased were transferred aboard an Italian navy ship headed for Sicily, where it is expected to dock later in the day.
Coast Guard spokesman Filippo Marini told Efe that "last weekend, 5,629 immigrants were rescued," while he added that on Sunday alone, the National Relief Centre of the Coast Guard coordinated rescues for 22 vessels.
Large numbers of illegal asylum-seeking immigrants set off from North African ports to nearby Italian coasts.
According to data released by the Italian interior ministry, 12,616 illegal immigrants arrived in Italy between January and April 7 in 2015, compared to 11,695 during the same period in 2014.