Marlborough police warn of poorly-made counterfeit $50 notes in circulation

Malborough Police are warning people to be wary of $50 notes used to pay after a number of counterfeit bills were found.

The fake bills have been used in Kaikoura and Blenheim this week, police said.

The notes look similar to an old-style $50 bill, but the transparent plastic window - which should have "50" in it - instead has a "20".

"Check all $50 notes - if in doubt you are not obliged to take them," Police said.

"Report any use of them to the Police immediately and save any CCTV footage you have in your store that covers the illicit transaction.

"If you have received one, place the illegal note in a plastic bag and reduce handling so we can recover fingerprints of the offender."