DAKAR - Around 40 West African migrants were feared dead, many from hunger and thirst, after their boat spent 12 days at sea in a failed bid to reach the Canary Islands, police said on Tuesday.

The fishing boat set off from the southern Senegalese region of Casamance and ran aground in the outskirts of the capital Dakar on Saturday after its captain turned back to save the remaining passengers.

"The survivors said there were around 40 dead and they threw their bodies overboard," police spokesman Colonel Alioune Ndiaye said. Some victims died of hunger and thirst after they ran out of food and water, he said.

"Among the dead were 10 Ghanaians who couldn't stand it any longer after 12 days at sea and threw themselves into the water."

Most of the 90 people on the boat when it arrived in the coastal town of Yoff ran away to avoid detention.

Police have cooperated with EU officials to curb smuggling after more than 30,000 illegal migrants landed on the Canary Islands last year -- six times more than in 2005.

European border agency Frontex said its sea patrols had cut the number of migrants arriving on the Spanish archipelago by nearly 70 percent in 2007.

Boats have increasingly been leaving from less well-policed shores such as in Gambia, which is not part of the Frontex policing system, said Abye Makonnen, regional representative for the International Organisation for Migration.

Gambia juts into central Senegal north of Casamance with a short Atlantic coastline.

DASHED DREAMS

Thousands of West Africans have died trying to escape one of the world's poorest regions and build a better life in Europe.

Scores of wooden fishing vessels attempt the perilous crossing to the Canary Islands each year, most of them laden with young men fleeing rampant unemployment or driven by social pressure to provide for their families.

Smugglers often charge migrants large sums. Experts say it can range from 800 euros (577 pounds) for a simple passage to many times that amount for false documents and other services.

The captains of the open boats often fail to equip the boats with navigation devices, reliable motors or enough fuel.

"These networks are often funded by a wide range of criminal activities -- drug smuggling, people trafficking, smuggling of weapons," said Amado Philip de Andres, deputy regional representative for the United Nations Office on Drugs and Crime.

He was speaking after a meeting of senior judges and prosecutors from across West Africa who were trying to draft better laws to combat human trafficking and migrant smuggling.

U.N. refugee agency UNHCR said measures by European governments to curb irregular migration and combat people trafficking could prevent refugees from entering EU territory.

UNHCR urged Slovenia, which will take over the EU presidency next month, to ensure that interception missions at sea and on land did not jeopardise asylum rights.