ASB Bank said it had detected a serious case of fraud by an investment advisor providing advice to customers "involving several million dollars."

ASB said the offending involved 22 customers, who had been identified and received restitution where irregularities had been confirmed. "We will continue to work with them to ensure that no customer is adversely affected," ASB said.

ASB said it had sacked the employee who had worked for the bank for more than 10 years, who was also now under investigation by the Serious Fraud Office.

"The fraud was elaborate and involved the investment adviser making fictitious investments on behalf of customers," ASB said, adding the employee had acted alone.

ASB confirmed this case is unrelated to one reported in the NZHerald on Monday evening of a 67 year old South Island man who was stopped from leaving the country after allegedly committing a multi-million fraud involving 'advanced fee' payments.