The ANZ bank has launched an internal investigation into claims staff have used Facebook to spy on customers.

It is alleged one of the bank's Melbourne-based debt collectors set up a fake account on the social networking site to covertly gather debtors' addresses, phone numbers and emails.

More than 80 people added "Max Bourke" as a contact before the fake profile was removed from the website yesterday.

ANZ spokesman Stephen Ries says several staff members are under investigation for their role in the online spying.

"We're taking this matter very seriously," he said.

"We are conducting internal investigations and appropriate disciplinary action will be taken once the investigation is concluded."