As many as 70 migrants have drowned after their boat capsized in the Mediterranean Sea, according to a UN migration official and Tunisia's state news agency.
At least 16 other people have been rescued.
An official with the International Organisation for Migration (IOM) in Tunisia said the smuggling boat was coming from Libya when it sent a distress signal in international waters off the Tunisian coastal city of Sfax.
The official said between 60 and 70 people drowned.
State news agency TAP said 70 people drowned as the boat sank and that fishing boats rescued 16 people.
The IOM official said the migrants are now being questioned and cared for by Tunisian authorities.
She said the migrants included people from Bangladesh and Morocco, among other nationalities.
At least 70 migrants dead after boat sinks off Tunisia https://t.co/83IVIV9w1k— Nigerian Diary (@NigerianDiary) May 10, 2019
The IOM said it was the deadliest migrant boat sinking since an incident in January when 117 were reported missing and presumed dead.
It comes as overall migrant arrivals to Europe are decreasing.
So far this year, 17,000 migrants and refugees have entered Europe by sea, about 30% fewer than the 24,000 arriving during the same period last year, according to the IOM.
It said 443 people have reportedly died on dangerous Mediterranean Sea crossings so far this year, compared to 620 deaths for the same period in 2018.
Libya's navy said it had rescued 213 Europe-bound African and Arab migrants off the Mediterranean coast this week. It said they were handed over to Libyan police after having received humanitarian and medical aid.
Dozens feared dead after boat sinks in Mediterranean - reports
Dozens of migrants are feared to be dead after their boat sank in the Mediterranean Sea, according to reports.
It is understood that at least 50 people are believed to have died after the boat went down off the coast of Tunisia.
The bodies of four people who drowned have been recovered so far, a spokesman for the country's defence ministry told AFP news agency.
The boat, which capsized off the coast of Kerkennah, is thought to have left from Zuwara, #Libya, according to the Tunisian Ministry of Defense.
It is understood there are 16 survivors of the accident.
Another tragedy in the #Mediterranean: @UNmigration's office in Tunisia reports that at least 50 people have died off the coast of Kerkennah after a boat from #Libya capsized. There are only 16 survivors.#MissingMigrants— Missing Migrants Project (@MissingMigrants) May 10, 2019
This latest tragedy comes after a recent UN report revealed an average of six migrants died crossing the Mediterranean every day last year.