Spanish police have rescued 39 women and girls smuggled in from Nigeria and trafficked into sex work by a notorious Nigerian gang.
Europol says the victims were kept in “squalid conditions in caves” and intimidated with voodoo threats.
Gang members forced the women into sex work in order to pay off a 30,000 euro ($37,000; £26,000) debt.
Eighty-nine people, including a famous but as yet unnamed Nigerian DJ, have been arrested.
The DJ is said to have helped move victims to Spain and organise sexual exploitation across the country.
He was caught flying back into Spain after recording a music video.
Investigations began when an underage victim filed a complaint with the police, saying she had been pressured into trafficking by voodoo threats made in Nigeria.
Along with other victims, the girl was transferred from Nigeria to Spain via Libya and Italy.
It follows a BBC investigation into the organisation.
The operation, which was carried out with police from the UK and Nigeria, is one of the biggest trafficking busts in Europe, says Europol.
It says 41 house were searched in 11 Spanish cities and one city in the UK.
According to Europol, the criminal cartel had links to the Eiye brotherhood, one of the most influential groups in Nigeria.
The gang was allegedly operating all over the world and pumping money back into the network.
Bank accounts allegedly used to illegally transfer more than 300,000 euro ($370,000; £260,000) have been blocked.