A Bulgarian human trafficking ring that allegedly operated a large prostitution network on Spain's Canary Islands has been dismantled by Spanish and Bulgarian police, the Interior Ministry said Tuesday.

Spanish authorities have arrested and charged 33 suspects, including 15 Bulgarians, the country's top police officer, Valentin Petrov, told a news conference.

The ring — allegedly led by 35-year-old Bulgarian, who was not identified by name — is suspected of organizing the smuggling of more than 500 women from eastern European countries into Spain, where police said the victims were treated as "sex slaves."

"The women's freedom of movement was restricted, and they were often subjected to violence," Petrov said, adding that they were forced to work as prostitutes.

Spanish police have been investigating the group for two years in a joint operation with Bulgarian colleagues, Petrov said.