Police said in a statement that they began investigating in 2022 and uncovered a well-organised and violent international criminal network of Chinese origin known as the "Tian Xia She triad".

The gang deceived the young women promising them a better future in Europe and captured them with the aim of selling them into prostitution rings in Greece, Spain and the United States.

The victims, all of Asian origin and including a minor, were forced to work as prostitutes "in conditions bordering on slavery" in Spain to pay off debts of up to 20,000 euros ($21,000) to their exploiters.

The gang obliged them to remain available for prostitution 24 hours a day without protection, prevented them from leaving the brothels and in some cases forced them to abort through surgery.

The network also made large profits by charging people, mostly from China, to smuggle them to Europe through the Balkans with a view to reaching the United States via Central America.

Drug trafficking was the other main income source of the gang, which employed minors to sell substances including ketamine or so-called "holy water", used to curb sexual inhibition and with a price of around 300 euros per dose.

EU law enforcement agency Europol collaborated in the police operation, which shut down two flats used as brothels and a document forgery facility following 14 raids in Spain and another in Croatia.