Africans, who reached the southern part of Spain, were first transported across the country to the town of Irun, located in the Basque Autonomous Community on the border with France. Then, they were sent by car, train, or passenger bus to Bayonne in the French Basque Country.
The ring members are believed to have transferred hundreds of migrants to the neighbouring country this way.
The criminal groups were independent, but they interacted with each other. They charged 200 euros ($236) per person, sometimes receiving money when migrants were still in Morocco.
In total, fifteen people linked to the criminal rings have been detained across Spain, with two leaders remanded in custody.