At least 20 African migrants died after their boat sank off the coast of Tunisia.

They were trying to cross the Mediterranean making their way towards the Italian island of Lampedusa, a Tunisian security official said on Thursday.

The coastguard rescued five people, ministry spokesman Mohamed Zekri said, adding that a search operation is still underway for about 20 others who were on board the boat, which had about 45 people.

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The coastline near the Tunisian port city of Sfax has become a major departure point for people fleeing conflict and poverty in Africa and the Middle East and searching for a better life in Europe.

"The boat sank about 10km from the coast of Sfax. Twenty bodies were recovered, five others were rescued, and all are from sub-Saharan Africa," the security official, Ali Ayari, said.

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