Several migrants have been found dead and around 40 rescued from a boat off Cape Verde, authorities said Tuesday, with fears dozens more may have died.

Cape Verdean media reported that the "pirogue" style boat common in the region left Senegal a month ago, while police said about 100 people had set off from the West African coast.

Senegal's foreign ministry said late Tuesday that 38 people, including a citizen of Guinea-Bissau, were rescued from the migrant boat off the Cape Verde coast.

The vessel was spotted on Monday almost 200 miles from the island of Sal by a Spanish fishing boat, which alerted Cape Verde authorities, police said.

Around 40 survivors and several dead bodies were found on the boat, but sources differed on the exact number.

The coast guard said the total number of survivors and dead was 48.

The local morgue said it had received seven dead bodies.

Jose Rui Moreira, a health official in Sal, said there were 38 survivors and seven needed to be taken to hospital.

Thousands of migrants fleeing poverty and war risk their lives to make the dangerous crossing each year.

The migrants were from Senegal, The Gambia, Guinea-Bissau and Sierra Leone.