"The illegal migrants, who spent over a week at sea, died of thirst and heat stroke," the radio said.
Among the dead, Spanish rescuers recovered seven surviving Africans adrift in a boat eight miles from the islands. All were hospitalized.
Hundreds of migrants, mostly from West Africa, die of thirst, hunger or sunstroke or due to lack of navigation skills while trying to cross the Atlantic Ocean to the Canary archipelago on motorboats.
Under agreements reached in 2006 between Spain and a number of West African nations, all illegal migrants reaching the Canaries must be immediately repatriated.