Officers said 35 of those arrested were sex workers from the mainland who were smuggled into Hong Kong by syndicate members.
Senior superintendent Ho Chun-tung said it was difficult to detect such illegal activities as the prostitutes were kept inside hotel rooms and flats in order to minimise the chance of them being stopped and searched on the streets.
He added that all advertising was done through instant messaging apps, such as Telegram and WeChat, as well as porn sites hosted outside Hong Kong.
Ho said this proved a “very, very big hurdle”, noting that the instant messaging companies were also not based in Hong Kong.
Around HK$6.5 million of crime proceeds was seized in the police operation.