At least six migrants have died trying to reach Spain's Canary Islands using precarious boats from West Africa, the emergency services and the Red Cross said on Wednesday.

Five of 65 migrants aboard an open-topped boat that reached the tiny island of El Hierro overnight were found dead, said the emergency services, while another migrant was found dead in one of three other vessels rescued by the Spanish coastguard.

The number of migrants reaching Spain's Canary Islands hit an all-time annual high for a second year in a row in 2024 and the seven islands off northwestern Africa are struggling to absorb a surge of people arriving on crammed boats seeking better opportunities in Europe.

But the number of migrants going missing or dying on the voyage is growing five times faster than the number of those arriving alive, the latest available data show.

The Atlantic route is especially dangerous as rough weather can easily capsize the fragile rafts, pirogues and dinghies used by most migrants.

So far this year around 20,000 irregular migrants have arrived in El Hierro, according to the Red Cross. That's about half the total of more than 40,000 who reached the archipelago over the period.