Police are investigating after Westpac mistakenly deposited a large sum of money into a business account, the owners of which have since left New Zealand.
Rotorua police will not say how much the sum is, but are not denying reports that it could involve millions of dollars.
Police will not reveal which country the account's owner is thought to have left for. They are seeking assistance from Interpol.
Detective Senior Sergeant David Harvey says some of the money has been withdrawn.
He says an investigation is under way into people who have have been involved in that withdrawal, but cannot name them or the Rotorua business.
Westpac will not confirm or comment on the investigation.
Police inquiry into bank's handling of deposit