Five women from South Korea, aged between 30 and 38, were arrested by Hong Kong police in a two-day special operation as part of a broader investigation into a syndicate that netted millions from prostitution.

After a six-month investigation, the police have arrested a total of 71 people in a prostitution ring based in West Kowloon that made more than HK$100 million (US$12.88 million) over the past year, Sing Pao Daily reported Thursday.

The police seized HK$650,000 cash, condoms, drugs and a car during the raids and froze the syndicate’s bank accounts with HK$2.5 million. It arrested the mastermind, a 43-year-old man surnamed Hung, who was believed affiliated with a local triad group, and five accomplices.

Customers included doctors, bankers and other high-income professionals, the police said, citing a customer list. Each transaction cost between HK$3,000 and HK$10,000. The syndicate, which recruited Korean women from porn websites, took a commission up to 60 percent, Sing Pao reported.

The arrested women include 56 mainlanders, four locals and five Koreans, the police said in a media briefing on Wednesday.