A boat carrying 86 migrants has sunk in the Mediterranean Sea off Tunisia, with 82 people missing.
Fishermen discovered the sinking vessel, 15 kilometres from the town of Zarzis on Wednesday evening.
The fishermen rescued four people who were on the boat but there was no other trace of passengers, said Lorena Lando, head of the International Organisation for Migration.
One of the four, a man from the Ivory Coast, died while the other three remain in hospital.
The boat is thought to have left from the Libyan city of Zuwara.
Libya has been marred with violence since long-time leader Muammar Qaddafi was overthrown and killed in 2011.
But a recent surge in conflict has led aid workers to warn that more Libyans may flee their country for Europe.
The boat sinking came a day after an air strike on a Libyan detention centre killed at least 44 migrants and wounded at least 130.
UN Secretary General Antonio Guterres on Wednesday denounced the "horrendous" attack and demanded an independent inquiry.
The UN’s High Commissioner for Human Rights, Michelle Bachelet, said that the attack may “amount to a war crime”.
Libya's government is considering closing all of its migrant detention centres after reports that guards shot at detainees trying to escape the bomb.
In May, at least 65 migrants drowned after their boat capsized when it was heading to Europe from Libya.