A boat carrying up to 70 migrants from sub-Saharan Africa has sunk in the Mediterranean, leaving at least three people dead and dozens missing, Tunisian officials said Friday.

The bodies of three people who drowned in the accident were found Friday, a spokesman for the Tunisian defense ministry said, adding the boat left Zwara on the northwestern Libyan coast on Thursday.

There were conflicting reports on how many people had been rescued and how many were missing, but the Guardian of Britain quoted the United Nations immigration agency as saying 16 survivors had been pulled from the water by fishing boats.

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Thousands of migrants have died trying to cross the Mediterranean from the coast of war-torn Libya to European soil, many landing on Italy's coast. In February last year a similar sinking left about 90 people dead off Libya's coast.

Mass migration to Europe has dropped sharply since 2015, when the continent received 1 million refugees and migrants from countries in the Middle East, Asia and Africa. The surge created a humanitarian crisis in which desperate travelers frequently drowned and leading arrival spots such as Italy and Greece struggled to house large numbers of asylum-seekers.

Along with the dangerous sea journey itself, those who attempt to cross the Mediterranean risk being stopped by Libya's coast guard and held in Libyan detention centers that human rights groups have described as bleak places where migrants allegedly suffer routine abuse.

EU members "alert the Libyan coast guard when refugees and migrants are spotted at sea so they can be taken back to Libya, despite knowing that people there are arbitrarily detained and exposed to widespread torture, rape, killings and exploitation," Matteo de Bellis, an international migration researcher for Amnesty International said earlier this year.

Humanitarian organizations say migrants are mistreated and even tortured in Libya, and have protested protocols to return migrants rescued offshore to the lawless northern African nation. Meanwhile, both Italy and Malta have refused to open their ports to humanitarian ships that rescue migrants at sea, which has created numerous standoffs as European governments haggle over which will take them in.