The boat overturned on Wednesday midnight near Jinack village in the North Bank Region and it was later found "grounded on a sandbank", the country's defence ministry said in a statement.
Ninety-six people have been rescued so far and a search is continuing for other passengers who were aboard the shipwrecked vessel that was heading towards Spain's Canary Islands.
The perilous journey over the Atlantic Ocean has become an increasingly common route for African migrants trying to reach Europe.
