ANZ has admitted that a staff member set up a fake Facebook account designed to entrap customers that had changed address without informing the bank.
Fairfax newspapers reported that debt-collection staff set up a fake profile, using the name Max Bourke, attempted to befriend customers with credit card and personal loan debts in a bid to discover their whereabouts.
An ANZ spokesman confirmed that the bank was aware of the fake profile, adding that it was created by a 'rogue' member of staff in its unsecured debt collections team.
"This type of rogue activity is neither approved nor sanctioned by ANZ and it is completely unacceptable," the spokesman told ninemsn.
"The Facebook page has been removed and we are currently completing an internal investigation."
It is not known how many ANZ customers were befriended by Max Bourke, but Fairfax reported that a "large number" were added as friends to the fake profile.
The spokesperson would not confirm how many customers had been affected and would not guarantee that there were no other fake Facebook profiles targeting the bank's customers.
These issues would be dealt with via the bank's internal investigation, he said.
"Disciplinary action will be taken where any staff member is found to have breached of ANZ's code of conduct and our policy on the use of technology.
"We are taking this matter very seriously and we'll take appropriate disciplinary action when the internal investigation is concluded."