More than 1,000 west Africans washed up on the shores of the Canary Islands this week, triggering a new immigration crisis for Spain and fresh misery for the migrants, who face an uncertain future in overcrowded detention camps.

Many migrants were rescued after their flimsy vessels capsized or sank in the perilous 300-mile journey from Mauritania - the latest launch pad for Africans attempting to reach Europe. Spanish officials estimate that west Africans are waiting to attempt the crossing, after Morocco and Algeria closed the northern migration routes to the Mediterranean last year.