Story highlights A large ship reportedly went down between Libya and Italy

The United Nations refugee agency interviewed the 41 survivors -- 40 adults and a 3-year-old child

The survivors, mostly north Africans, were taken to Greece, U.N. says

(CNN) As many as 500 migrants may have died when a large ship sank in the Mediterranean last week between Libya and Italy, the United Nations refugee agency said Wednesday.

On Tuesday, a U.N. team interviewed survivors of what could be one of the worst tragedies involving refugees and migrants in the last 12 months.

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The 41 survivors -- 37 men, three women and a 3-year-old child -- were rescued by a merchant ship Saturday and taken to Kalamata, Greece.

Those rescued include 23 Somalis, 11 Ethiopians, 6 Egyptians and one person from Sudan, the U.N. High Commissioner for Refugees said.

Disaster came as smugglers transferred people to another boat at sea

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