Four migrants have died and several hundred been rescued from four boats off the Canary Islands, Spain's emergency services said on Saturday.

Two vessels carrying a total of 254 migrants in good health were intercepted on Friday evening and escorted to Restinga port on El Hierro island, rescuers said on X, formerly Twitter.

At dawn on Saturday a third boat loaded with 238 migrants was located and escorted to safety.

Thirteen people were hospitalised, and two died despite medical treatment, the rescuers said.

Two people also died aboard a fourth vessel on Saturday morning. The rescue services did not give a figure for the number of migrants on board.

As controls have been tightened in the Mediterranean, the Canaries route has become a favourite for people fleeing poverty and conflict in Africa -- most of them on overcrowded, barely seaworthy vessels.

Data from Spain's interior ministry show 30,705 migrants reached the Canaries between January 1 and October 31, more than double the number of arrivals for the same period of last year.

The first fortnight of this month alone saw 8,561 arrivals -- a record for a two-week period since a previous migration crisis in 2006.