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.

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

The survivors told U.N. officials they had been part of a group of between 100 and 200 people that departed last week on a 30-meter boat from a site near Tobruk, Libya.

After sailing for several hours, the smugglers in charge of the boat attempted to transfer the passengers to a larger ship already carrying hundreds of people in overcrowded conditions, the U.N. agency said.

During the transfer, the larger boat capsized and sank, the agency said.

The 41 survivors include people who had not yet boarded the larger vessel, as well as some who managed to swim back to the smaller boat. They drifted at sea for as long as three days before being rescued, the U.N. said.

UNHCR visited the survivors at a stadium in Kalamata, where they’re being housed by local authorities while they undergo police procedures.