The Italy on Friday in Rome confirmed the death of 12 migrants on Thursday when their overcrowded rubber dinghy sank off the coast of Libya.
It said no fewer than 500 others were rescued in the latest episodes in the Mediterranean migrant crisis.
Italian coast guards said the corpses of the victims were found in the sea by the Coast Guard ship, Dattilo, some 40 miles north of Libya.
The organisation said Dattilo saved 106 people from the same dinghy, which was half submerged when help arrived.
No details were available on the nationalities of the victims or those rescued.
It said Dattilo was still involved in other rescue operations involving boats in difficulty.
A total of 393 other migrants were saved in four different operations carried out by the Dattilo on Thursday.
Similarly, while another 106 migrants were saved by two Coast Guard frigates operating off the southern Italian island of Lampedusa.
Tens of thousands of migrants fleeing war and hunger in Africa and the Middle East have crossed the Mediterranean to Italy and Greece in 2015.
Reports say investigation revealed that the vast majority of them are departing from the coast of Libya and no fewer than 2,000 migrants are estimated to have drowned.