At least 14 counterfeit $100 notes have now been passed in to Canterbury Police Fraud Squad since the middle of June and police are concerned that staff at dairies and small shops should take care when accepting $100 bills.
Detective Sergeant Virginia Le Bas says that whoever is passing the counterfeit notes over is buying small items under $10 and collecting a large amount of genuine change.
"I'd caution shops not to accept $100 notes from anyone they do not know," she says. "They are generally not very common in circulation and most money machines don't dispense them."
Detective Sergeant Le Bas advises anyone with notes they are unsure about to check them with their bank.
"For a small business, $100 is a lot of money to lose."