Most of the latest batch of migrants were picked up overnight from two wooden boats travelling together and around 40 people were rescued from another boat at dawn.
Around 400 were rescued by the Aquarius, a rescue boat operated by charity SOS Mediterranee, which said the migrants it had taken on board included Eritreans, Bangladeshis, Pakistanis, Somalians and Syrians.
According to the Italian Interior Ministry, some 180,300 migrants had been registered this year at Italian ports prior to the latest rescues. This compares with a previous annual record of 170,100, recorded in 2014.
UN bodies say more than 5,000 people have died trying to cross the Mediterranean, most of them on the Libya-Italy route. The Libyan Red Cross said on Wednesday that 11 drowned bodies had been found on beaches near Tripoli in the West of the country.