The Reserve Bank is warning Canterbury retailers to be wary of fake banknotes after upwards of 50 counterfeit bills were accepted over the past fortnight.
"New Zealand's banknotes and coins are among the most secure in the world, and counterfeits rates are extremely low," said Reserve Bank Head of Banking Steve Gordon in a statement.
However, he is urging Canterbury retailers to be vigilant.
He warns to check the bank notes before they are accepted using the "Look, feel, tilt technique."
"Looking at a genuine note you should see a window with the bird and value matching what's on the note," he said on Friday.
"The note and window will feel like plastic and smooth except for the denomination printing, and when you tilt the note a coloured bar will appear to move up and down the smaller printed bird."
The counterfeits that had been accepted were picked up as they hit retailers back offices and the banking system, so no ATM issues have arisen.