Nine people have been arrested in England and Spain on suspicion of human trafficking offences connected to an escort agency.
West Midlands Police worked with Spanish officers and the National Crime Agency to carry out the arrests.
It is alleged heads of an organised crime group trafficked women within the UK and forced them into sex work.
Det Con Steve Oldbury said the group was believed to have “netted thousands of pounds a week”.
In Madrid, police arrested a man and a woman, both 43, while British officers executed warrants across the West Midlands and south of England.
A 68-year-old man was arrested in Kent and a 50-year-old man in Tamworth.
Three men, aged 28, 29 and 55, were arrested in Sandwell and two men, 41 and 46, in Birmingham.
All were detained on suspicion of conspiracy to control prostitution, conspiracy to traffic within the UK for sexual exploitation and money laundering offences.
They remain in custody for questioning, with extradition proceedings under way for the pair arrested in Spain.
Det Con Oldbury said: “We believe the group has netted thousands of pounds a week with funds regularly and illegally transferred out of the country.
“At the heart of this criminality is the women who are alleged to have been coerced and intimidated into performing sexual services. Their welfare is of the utmost concern.”
Neil Keeping, National Crime Agency Regional Manager for Spain, said organised crime groups sexually exploited victims both in the UK and overseas.
“Victims are often seeking a better life, but are instead forced into the sex industry where they are controlled and exploited by offenders who treat them as commodities in the pursuit of profit.”
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