The Coast Guard rescued five people and was looking for about 20 others who were still missing, the official said.
“The boat sank about ten kilometers off the coast of Sfax. Twenty bodies were recovered, five others were rescued, and all are from sub-Saharan Africa,” said security officer Ali Ayari.
About 45 people were on the boat when it sank, he added.
The coastline at the Tunisian port city of Sfax has become an important starting point for people fleeing conflict and poverty in Africa and the Middle East and looking for a better life in Europe.
Countries like Italy and Malta have seen an increase in sea arrivals this year from Tunisia – where high unemployment and precarious socio-economic conditions have triggered migration – and from Libya, where conflict and war were a major factor, according to figures from the United States. Nations High Commissioner for Refugees (UNHCR).
Thursday’s deaths add to the already long list recorded this year, even with Covid-19 travel restrictions.
According to the IOM, the boat would transport more than 120 people, including women and children.
Soda called for a change in the “unworkable approach to Libya and the Mediterranean, including ending returns to the country and establishing a clear disembarkation mechanism followed by solidarity from other states.”
“Thousands of vulnerable people continue to pay the price for inactivity, both at sea and on land,” he said.
Migration-related deaths are often under-reported and unrecorded, according to the IOM, which also said the pandemic has made it more difficult to collect that data.
CNN’s Emma Reynolds and Sharon Braithwaite contributed to this report.