The cards, suspected to belong to the three as well as other people, were impounded as part of the operation, along with bank documents and mobile phones.
The force on Friday arrested the three – aged between 28 and 47 who all entered the city from Shenzhen through two-way permits – in Wan Chai for conspiracy to launder money after an investigation and intelligence analysis.
The three were still in custody on Saturday.
The force warned the public that the use of personal bank accounts or allowing accounts to be used by others for illegal purposes may constitute money-laundering.
The maximum penalty on conviction is 14 years behind bars and a fine of HK$5 million (US$641,506).
It also appealed to the public and financial institutions to report any suspicious accounts or bank transfers.
Police earlier this month arrested seven people for alleged involvement in a HK$100 million international money-laundering syndicate behind technical support scams.
Among those arrested for conspiracy to launder money were people alleged to be the mastermind, three members of the syndicate and three mules, aged between 33 and 43.
