More than 70 survivors were rescued by a freighter off the coast of Sicily.
The migrants said they had been at sea for nine days, but a quarter of those on board died on the way, and the survivors threw their bodies overboard.
The Italian authorities believe the boat began its journey in Libya. Those on board were mainly from Sudan, Sierra Leone, Liberia and Ivory Coast.
“My son didn’t make it. I had to abandon him in the sea,” one survivor told Ansa news agency.
Small boats carrying illegal migrants regularly take people from North Africa to Italy.
Migrants pay people-smugglers hundreds of dollars in search of a better life.
Hundreds of people, mainly from Africa and Asia, have already tried to make the journey this year. An unknown number have died.