By Borja Suarez and Graham Keeley
EL HIERRO, Spain (Reuters) - Hopes of finding any of the 48 migrants missing since their boat sank near the Spanish island of El Hierro are diminishing, authorities said on Sunday, in what threatens to be the deadliest such incident in 30 years of crossings from Africa to the Canary Islands.
Nine people, one of them a child, had earlier been confirmed as dead after the boat sank in the early hours of Saturday morning, emergency and rescue services said.
Rescuers were able to pick up 27 of 84 migrants who were trying to reach Spanish shores on Saturday. Three patrol boats and three helicopters were taking part in a renewed search for the others on Sunday, a Spanish coastguard spokesman said.
"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 migrants were from Mali, Mauritania and Senegal, Spanish authorities said.
The number of migrants crossing from West Africa to the Canary Islands increased by 154% from January to July, totalling 21,620 in the first seven months, data from the European Union's border agency Frontex showed, while numbers fell on routes in the central and western Mediterranean during the same time.
Crossings from Turkey to Greece rose by 57% and over the English Channel to Britain by 22%.
Shortly after midnight on Saturday, Spanish emergency services received a call from the boat, which was located around four miles east of El Hierro. It sank during the rescue attempt, they said. Wind and poor visibility made the rescue extremely difficult.
"After what happened yesterday and if the forecast for the arrival of the migrant boats happens, then it will be the biggest humanitarian crisis to happen to the Canary Islands in 30 years," Candelaria Delgado of the Canary Islands government, told reporters on Sunday.
Three of those rescued suffered from hypothermia and dehydration, rescue services said on Sunday.
The nine migrants who died will be buried on Monday and Tuesday. Among the dead was a child aged between 12-15, according to the NGO Walking Borders, which helps migrants.
As hopes of finding more survivors ebbed, police set up a morgue on El Hierro, authorities said.
Three other boats reached the Canary Islands during the night, carrying 208 migrants.
Calm seas and gentle winds associated with late summer in the Atlantic Ocean off West Africa have prompted a renewed surge of migrants, local authorities said this month.
In some 30 years of migrant crossings to the islands the deadliest shipwreck recorded to date occurred in 2009 off the island of Lanzarote when 25 people died.