At least 24 people seeking to reach Europe drowned off northern Senegal when their loaded vessel sank, the governor of the Saint Louis region told AFP on Thursday.

Governor Alioune Badara Samb said 24 bodies had been found since Wednesday after the boat got into difficulty in a particularly dangerous part of the northern coast.

The Saint Louis estuary, where the Senegal River meets the Atlantic Ocean, is notorious for its strong currents and areas of thick mud.

Samb did not say how many people were missing from the vessel, which witnesses said could have been carrying more than 300 people.

A number of survivors managed to reach shore and dispersed among locals on the banks, making it difficult to say exactly how many people were involved, he said.

Mamady Dianfo, a survivor from Casamance in the south, told AFP there were more than 300 people on board when the boat left Senegal a week ago.

Another survivor, Alpha Balde, estimated there were more than 200 passengers.

Dianfo said the vessel reached Morocco, further north up the coast but the captain then said he was lost and could no longer continue the journey.

"We asked him to take us back to Senegal," he said.

Senegal's coast is an increasingly common departure point for Africans fleeing poverty and unemployment and heading to the Canary Islands, their port of entry into Europe.

European Union border agency Frontex says Senegal and Morocco are the most common countries of origin for migrants arriving on the Spanish archipelago in the Atlantic.

Of the more than 6,600 migrants who died or went missing trying to reach Spain last year, the vast majority were lost on the treacherous Atlantic route, according to Spanish NGO Caminando Fronteras.