Spanish police announced on Friday that they have dismantled two human smuggling rings believed to have facilitated the crossing into France of hundreds of irregular immigrants.
The two smuggling networks operated from Bilbao and Vitoria, two cities in the north-western Basque County.
Fifteen people have been arrested including three in the Spanish capital, Madrid, and one in Lleida, a city in the north-eastern province of Catalonia.
"The migrants arrived by boats at different points on the Spanish coasts, where they were referred to different NGOs," the police said in a statement.
"It was there, or even before their departure from Morocco, that the networks enticed them with the promise of moving them from Spain to France for a price of around €200," it added.
One of the networks used cars to cross the border and bring the migrants to the French city of Bayonne. The other smuggling ring provided them with bus tickets to Bayonne and instructed them to only travel at specific time slots.
In both cases, the migrants would then go to a local NGO or to a reception centre until they received further instructions for their onward travel to their final destination in France or to another European destination.
Police estimate that "several hundred irregular immigrants have crossed the border between Spain and France through the support of these networks "which reaped "great benefits" from it.
The investigation was started after a man was arrested in Navarra, a province neighbouring the Basque County, who had been caught on multiple occasions smuggling people into France. They then uncovered the two smuggling rings, which sometimes cooperated with each other.
During the arrests, officers also recovered €3,000, a vehicle, 24 mobile phones and computer equipment.