Maritime officials are in Mauritania's economic capital of Nouadhibou to investigate the recent accident, while several survivors are receiving treatment.

Coast guard officials recovered four bodies in Mauritanian waters, including two Senegalese nationals.  The two other bodies were not immediately identified, while at least 24 other people were missing and presumed dead.

The boat, rented out by the victims, was a wooden pirogue. Survivors said it was overcrowded and trying to reach Spain's Canary Islands in stormy weather.

Journalist Salem Bokary says illegal immigration from sub-Saharan Africa, through North African countries, on to Europe has been intensifying.

"This is the most dangerous and the most important accident in the waters of Mauritani," he said.  "It concerns a certain number of immigrants, who are 45 persons, who left this weekend the economic capital of Mauritania, and who tried to get a job and a better life in Spain."

Illegal migration to Europe has been a main topic of concern in north and West Africa since September, when several migrants died after trying to force their way onto Spanish territory.  Six others drowned off the Canary Islands on a makeshift boat in November.