Thirty-seven people are missing after their boat capsized between Tunisia and the Italian island of Lampedusa, the International Organization for Migration (IOM) said on Friday, citing an account by four survivors of the shipwreck.

The UN agency said the survivors, all from sub-Saharan Africa, arrived on Lampedusa late on Thursday, having been rescued from the shipwreck by another vessel.

The shipwreck took place on Thursday and at least one newborn baby is among those missing, said UNHCR representative to Italy Chiara Cardoletti.

The vessel left from Sfax in Tunisia and was carrying 46 migrants from Cameroon, Burkina Faso and Ivory Coast, said Flavio Di Giacomo, a spokesperson for the UN migration agency IOM.

The boat capsized in strong winds and high waves, he said. “Some survivors were taken to Lampedusa and others were brought back to Tunisia.”

“Among those missing were seven women and a minor. The survivors are all adult men,” he added.

“We have noticed more arrivals of migrants from sub-Saharan Africa than Tunisians” via the Tunisian route since November, he said.

He explained this was due to people from sub-Saharan Africa fleeing discrimination in Tunisia.

“It is unacceptable to continue counting the dead at the gates of Europe,” Cardoletti said.

Earlier, the UN’s High Commission for Refugees gave a similar account of the same incident, but said 40 people were believed to be missing, rather than 37.

The southern Italian island of Lampedusa is one of the main entry points for migrants crossing the Mediterranean. Last year, more than 46,000 people arrived there, out of a total of 105,000 in Italy, according to the UNHCR.

There has been a rise in migration across the Mediterranean from Tunisia this year after a crackdown by Tunis on migrants from sub-Saharan Africa living in the country illegally and reports of racist attacks amid an economic downturn.

At least 12 African migrants were missing and three died after three boats sank off Tunisia, a judicial official said on Thursday, while the country’s coastguard rescued 152 others.

It was not immediately clear if the four survivors who recounted their story to the IOM were on one of these three boats.

Reuters and AFP contributed to this report