Italian navy helicopters spotted four overcrowded boats struggling to stay afloat south of Sicily on Thursday and ships were sent to save them, authorities said in a statement.
The 823 men, women and children aboard the four vessels were from countries including Egypt, Pakistan, Iraq and Tunisia.
The navy rescued 233 migrants from Eritrea, Nigeria, Somalia, Zambia, Mali and Pakistan in a separate operation and took them to a port near Syracuse on Sicily's eastern coast.
After the shipwreck in October in which 366 Eritrean migrants drowned off the Italian island of Lampedusa, Italy launched a special operation, combining ships, helicopters and drones, to monitor the Mediterranean Sea.
Italy is a major gateway into Europe for many migrants seeking a better life, and sea arrivals to the country from Northern Africa more than tripled in 2013, fuelled by refugees in Syria's civil war and strife in the Horn of Africa.
Over the past two decades, Italy, Greece and the Mediterranean island of Malta have borne the brunt of the migrant flows and have urged for a coordinated European Union response system.
Migrants in Israel protest against detention
In the meantime, thousands of African migrants, many holding banners demanding freedom for compatriots jailed by Israel, protested on Sunday in a Tel Aviv square against a new open-ended detention law which allows migrants to be sent to a desert prison.
The protests prompted a rare and strongly worded statement from the UN refugee agency, saying that Israel's incarceration of migrants, including family breadwinners, caused "hardship and suffering" and was "not in line with" a 1951 world treaty on the treatment of refugees.
Human rights groups say that more than 300 people have been arrested since the law, which allows authorities to detain migrants without valid visas indefinitely, was passed by Israel's parliament three weeks ago.
Dozens more have been summoned for detention, among them men with wives and children, rights activists and the UNHCR said.
Some 60,000 migrants, largely from Eritrea and Sudan, have crossed into Israel across a once-porous border with Egypt since 2006, Israeli authorities say.
Many live in poor areas of Tel Aviv and say they want asylum and safe haven. Prime Minister Benjamin Netanyahu has said he views the presence of many of the Africans as a threat to Israel's Jewish social fabric.
An Israeli border fence has cut off the African influx from Egypt since 2012, but migrants who have already crossed can be sent to what the government describes as an open prison in Israel's southern desert.
The new facility, which was the focal point of the protests by some 10,000 in Tel Aviv, is similar to a half-way house. Detainees can leave during the day but must report back by nightfall. Migrants can be held there without a time limit pending voluntary repatriation, implementation of deportation orders or resolution of their asylum requests.