Customs officers on Thursday said they had arrested four men suspected of laundering more than HK$400 million.

Officers said their investigation, which stemmed from another money laundering case at the end of last year, involved some 9,000 transactions through dozens of bank accounts, a virtual currency exchange trading platform and a local money changer.

Three men aged 21 and a 36-year-old man had been arrested.

Officers said the suspects' backgrounds and financial status were "highly incommensurate" with the large transactions they were probing.