The 28-year-old woman and her 21-year-old brother were arrested in an operation on Tuesday, when officers raided a flat in Yau Tong.

Initial investigations showed the accounts were opened between May and November last year, which they used to handle about HK$384 million. There were about 2,500 suspicious transactions handled via over 380 personal bank accounts.

When opening the accounts, the sister claimed she was an insurance agent and a telecommunications salesperson, although she was only a clerk back then. The brother, a university student, also claimed he was a salesman, a clerk and a logistic company staffer when bank staffers asked about his occupation.

The woman and man claimed they were paid HK$12,000 and HK$15,000 each month respectively during that period, but records showed that none of them filed tax returns. In one financial year, the brother filed that he made HK$1,400 income – which didn't match with the large sum of money he handled in the accounts.

According to customs, the brother also used an account on a virtual currency trading platform to handle HK$38 million.

Customs believed other criminals used the man's account to convert the virtual currency into US dollars. The US dollars were deposited into his bank account, before they were transferred to other personal and business bank accounts.

Officers froze HK$130,000 of assets. The duo has been released on bail and more arrests may be made.