The Italian coast guard says eight migrants have died after their dinghy got into trouble while trying to cross from Libya to Europe.
Dramatic video footage has been released by the service showing a rescue operation in which a further 84 people were pulled to safety.
Authorities say the migrants' vessel was spotted by a plane patrolling the seas off the Libyan coast on Saturday morning.
Hundreds of thousands of migrants have fled conflict or poverty at home and are now trapped in the north African state where they often face dire conditions, abuse and forced labour.
Most hope to pay people smugglers for passage to Europe via Italy.
In late December the United Nations began bringing African refugees to Italy from Libya, evacuating them from detention centres whose conditions have been condemned by humanitarian groups as inhumane.
Nigeria, whose citizens make up most of the African migrants, is this weekend beginning a mass evacuation programme for all those who want to return home. Up to 800 Nigerians are expected to be evacuated from the Libyan capital.
During a visit to Tripoli, Nigeria's Foreign Minister Geoffrey Onyema said: "we're going to be working together with the Libyan authorities and the International Organization for Migration to get precise numbers. Some of the difficulties with getting precise numbers are that some are within the control of the central government in camps, some are clearly outside the camps, some are also in less accessible areas where there might not be full central government control and authority."
Nigeria now joins Niger in organising bilateral returns
The International Organization for Migration (IOM) has in recent months acclerated a "voluntary returns" programme to repatriate migrants from a number of countries.