The Mediterranean is the world's most dangerous sea migration route: 1,357 people drowned or went missing since the start of the year, the International Organization for Migration (IOM) reported last week.
In a statement, the Italian Navy indicated that the death toll from the latest accident was provisional, as rescue operations were still ongoing.
A migrant boat in distress was spotted by a navy patrol unit just before it overturned because of "the high number of people on board," the navy said.
Its patrol vessel rushed to the scene with lifeboats and life jackets. Further rescue units, including a helicopter, were immediately deployed to support rescue attempts.
Migrant crossings to Italy have increased this week: late on Tuesday, the Italian Coast Guard said 5,600 people had been picked up from the sea since Monday, in 38 separate interventions.
Speaking before the latest rescue, IOM Rome spokesman Flavio Di Giacomo told dpa that there had been 39,600 migrant landings in Italy since the start of 2016, broadly stable from the same period of 2015.