A woman was the sole survivor after a migrant boat carrying at least 53 people capsized about 220km off the Canary Islands.
The woman was spotted in a poor state by a passing merchant ship and emergency services flew her to safety. She was found clinging to an upturned inflatable dinghy.
Two bodies were found by the coastguard and the woman told officials that more than 50 other people were on board.
More than 8,000 migrants have reached Spain’s Canary Islands this year alone.
Many of them set off from a stretch of coastline between Tarfaya in Morocco and Laayoune in Western Sahara, a disputed territory claimed by Morocco.
The route has become increasingly popular as migrant passages to Europe through the Mediterranean have become harder to take. However, human rights group Walking Borders has described it as the world’s most dangerous migration route.
The woman rescued on Thursday was taken to hospital suffering from severe dehydration.
The United Nations migration officials estimate more than 350 people have died this year trying to reach Spain’s Canary Islands, but Walking Borders believes it could be higher than 2,000.
Only this week, 47 people were feared to have died off the coast of Mauritania when a boat lost power and drifted for almost two weeks, until it was spotted by coastguards.