Sorry Kaba, a foreign ministry official in Dakar, told AFP "more than 200 Senegalese perished" in the worst migrant shipwreck recorded on the sea, earlier this month.
Some 1,750 migrants have died crossing the Mediterranean to Europe this year, 30 times more than during the same period in 2014.
At least 700 were killed on April 19 after their rickety trawler sank between Libya and southern Italy, sparking global outrage and demands for a solution.
"These networks do their planning in Senegal. The young people who get on board, it's their families back in Senegal who pay for their transportation."
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Mali's ministry for overseas nationals said in a statement 156 Malians had perished in recent Mediterranean accidents, most from the western region of Kayes, near the Senegal border.
Senegal said it was setting up a crisis centre and a hotline to enable families to get in touch with authorities who are "working hard to give people reliable and credible information".
The number of migrants crossing to southern Europe from Africa has shown little sign of easing since the April 19 disaster.
Media in Dakar have for several days been reporting the deaths of Senegalese in capsized vessels on the Mediterranean.
"Seventeen deaths for Goudiry" said a headline Monday in "Le Quotidien" over a story quoting a youth worker in the Senegalese district at the Mali border.
The area is the principal departure point for Senegalese trying to get to Europe, who then frequently travel east through Mali, Burkina Faso, Niger and finally Libya to catch boats.