Fifteen African would-be immigrants, including nine young children, died after their boat was left adrift by engine failure while trying to reach Spain, police said on Thursday.
Thirty-three survivors were rescued overnight about 50km off Almeria on the southern coast. They included a baby and 13 women, three of them pregnant.
Four of the survivors were reported in very serious condition. They included the baby and three of the women, one of whom had had a miscarriage.
The migrants were being treated for symptoms including hypothermia, dehydration and burns from the sun and fuel.
The survivors said they had been adrift for more than five days. They said they had thrown into the sea the bodies of 14 people who perished, including nine children aged between 12 months and four years.
The 15th victim, who was a woman, died before the police patrol boat that rescued the survivors reached Almeria.
Half of the survivors were described as being in very poor health. Most of the migrants had to be carried ashore. Psychologists were attending to the women who had lost their children on board.
The migrants came from several countries including Nigeria, Gambia, Kenya, Senegal and Cameroon.
The 6m-long rubber dinghy had set off from an unknown location on the North African coast. After weathering a storm, it suffered an engine failure, and the migrants began running out of food and water.
Police located the vessel after it had been spotted by a sailing boat.
Officials did not exclude the possibility that the survivors would not be expelled from Spain after recovering from their ordeal, despite repatriations being the norm in such cases.
The tragedy followed the deaths of 14 Nigerians, including four women and a minor, who went missing after their boat capsized on Monday.
At least 70 would-be immigrants have lost their lives while trying to cross over from Africa to Spain so far this year. The NGO Pro Derechos Humanos de Andalucia says 921 migrants died during such crossings in 2007.
The number of immigrant boats heading for Spain usually increases in the summer months, when the weather favours navigation.
About 18 000 would-be immigrants coming from Africa were detained in Spanish waters or on land in 2007, less than half the number arrested in 2006. Most of the immigrant boats were intercepted on Gran Canaria Island as well as Almeria and Cadiz provinces on the mainland.
Increased maritime surveillance and expulsions are believed to have helped to curb illegal immigration. — Sapa-dpa