Saturday's total was thought to be the highest for a single day in recent years as calm conditions encouraged people smugglers to leave Libya with boats stuffed with as many paying passengers on board as possible.
The coastguard said it had received distress calls from a total of 22 vessels, either inflatable dinghies or wooden former fishing boats -- all of them dangerously overcrowded and many of them lacking basic safety equipment.
Boats from the Italian coastguard, navy and customs police all took part in the rescue operation alongside Norway's Siem Pilot and Ireland's Niamh, ships serving with the EU's Triton search and rescue mission.
There were no reports of migrants having died during Saturday's operations or prior to the rescue boats arriving.
The wave of new arrivals triggered increasingly virulent attacks on centre-left Prime Minister Matteo Renzi's handling of the migration crisis.
"This must a joke. We are using our own forces to do the people smugglers' business for them and ensure we are invaded," said Maurizio Gasparri, a senator for Silvio Berlusconi's centre-right Forza Italia party.
Matteo Salvini called on the government to park the migrants on disused Italian oil rigs off Libya.
"Help them, rescue them and take care of them: but don't let them land here," the populist leader of the anti-immigration Northern League wrote on his Facebook page.
The rescued migrants included a batch of 311, including a newborn baby, who were on a boat belonging to humanitarian group Doctors without Borders (MSF) which is expected to dock on Monday in Vibo Valentia in Calabria, according to port authorities there.
A further 370 had been picked up by the Italian customs police and were headed for Messina in Sicily and the Norwegian boat Siem Pilot was also carrying hundreds of people to port.
Locked below deck
Just over 170,000 migrants and refugees from Africa, the Middle East and South Asia landed at Italy's southern ports in 2014 after being rescued in the Mediterranean, while the total for 2015 has already topped 104,000.
A further 135,000-plus have landed in Greece since January and more than 2,300 people have died at sea while trying to make it to Europe with the help of traffickers.
Police in Palermo, Sicily, announced Saturday that they had arrested six Egyptian nationals on suspicion of people smuggling following the rescue of a stricken boat on August 19.
Testimony from the 432 migrants on board suggest the vessel had been packed with more than 10 times the number of people it was designed for, with many of the passengers, including a number of women and children, locked below decks.
They had each paid the traffickers 2,000 euros ($2,200) for the passage from Egypt to Italy, according to statements given to police.
On board, the crew were reported to have demanded further payment to allow those locked in the hold to come up temporarily for air.
Humanitarian organisations say the surge in the numbers of people trying to reach European Union countries is the result of conflicts or repression in Africa and the Middle East.
They have called on European governments to shoulder more of the burden of absorbing the wave of asylum seekers and to help create safer routes for them to reach Europe.