At least 1,500 illegal immigrants who have sailed to the Canary Islands from Africa in recent weeks are to be set free by the Spanish authorities.
The sub-Saharan migrants will be flown to the mainland before being released and most hope to make their way to Britain, France, and Italy, officials told El Pais newspaper yesterday.
Some 3,800 illegal immigrants, mostly young men from Mali and Senegal, have arrived in the Canary Islands in small boats since the start of the year.
The Spanish Red Cross estimates that a further 1,300 have drowned during the perilous 500 mile voyage from Mauritania.
Thousands have risked the journey in small open boats after migration routes via Morocco were closed off by its improved co-operation with Spain.
About 2,500 sub-Saharan migrants are crammed into detention centres and military camps on the Canary Islands.
Spain has been repatriating small groups to Mauritania by chartered aircraft.
But, under its liberal immigration laws, illegal migrants can be held for a maximum of 40 days.
If officials then fail to establish their nationality, or discover that they come from a country such as Mali which has no repatriation agreement with Spain, they must be released. Most illegal arrivals will therefore have to be set free, officials said.
Once released on the Spanish mainland, the migrants can make their way through continental Europe because of the border-free Schengen zone. Britain is not part of the Schengen zone and maintains border controls with the rest of the European Union.