Forty-one migrants have died in a shipwreck off the Italian island of Lampedusa, survivors told local media.
A group of four people who survived the disaster told rescuers that they were on a boat that had set off from Sfax in Tunisia and sank on its way to Italy.
The four survivors, originally from the Ivory Coast and Guinea, reached Lampedusa on Wednesday.
More than 1,800 people have lost their lives so far this year in the crossing from North Africa to Europe.
The survivors – three men and a woman – told rescuers that they were on a boat carrying 45 people, including three children.
They said their boat left Sfax on Thursday last week, but sank within hours.
They added that they were rescued by a cargo ship and then transferred to an Italian coast guard vessel.
The Italian coast guard reported two shipwrecks in the area on Sunday, but it is not clear whether this vessel is one of those.
Tunisian authorities say Sfax, a port city about 80 miles (130km) from Lampedusa, is a popular gateway for migrants seeking safety and a better life in Europe.
In recent days, Italian patrol boats and charity groups have rescued another 2,000 people who have arrived on Lampedusa.
Tunisia has seen a wave of racism against black Africans in recent months and attempts to leave the country by boat have increased.