Rescuers were searching for at least 48 migrants from an overturned boat off the Spanish Canary islands on Sunday, but with diminishing chances of finding survivors.

"Unfortunately we presume the worst. The search goes on but it seems that the chances of finding someone alive are slim," a spokeswoman for the Canary Islands government told Reuters on Sunday.

The boat carrying 84 overturned on Friday night, killing at least eight adults and one child in waters near the El Hierro island. Search teams were able to save 27 migrants.

The incident could prove to be the deadliest from the past 30 years of migrant crossings to the Canary Islands — a group of Spanish-owned islands located just off the coast of Africa.

Spanish authorities said the migrants came from Mali, Mauritania and Senegal.

More bodies likely to show up

Regional president for the islands, Fernando Clavijo, told reporters on Saturday night that the 48 had been "presumed dead," and that more bodies would possibly appear over the next couple of days when they were washed up by the current.

Despite continued efforts on Sunday, no announcement of successful rescues had been made by nightfall.

Officials said the people on the boat had gone for two days without food or water and called the authorities themselves.

When rescuers arrived, those on the boat rushed to one side, causing it to tip and capsize.

Government sources also said the boat may have originally been carrying 90 people.

The boat had set off from Nouadhibou in Mauritania, about 800 kilometers (nearly 500 miles) away from Spain. This is the latest such accident off the northwestern coast of Africa.

The number of migrants crossing from West Africa to the Canary Islands increased by 154% from January to July, data from the European Union's border agency Frontex showed. At the same time, numbers fell for central and western Mediterranean routes.

tg/ab (AFP, AP, Reuters)