Fraudsters are targeting shops in West Bridgford with fake £20 and £50 notes.
Police say businesses in Bridgford Road, Central Avenue and Gordon Square have been hit with the con over the last few days.
Officers say they want to trace a man and a woman in connection with the fraud.
The man is white, in his early 20s and of medium build. He has been seen wearing a light coloured jumper, dark jeans and dark woollen hat. He spoke with an Irish accent.
The woman is of roughly the same age, of a thin build, with long dark brown hair. She has been seen wearing a dark parka-style coat with a fur-lined hood and jeans.
Anyone with information is asked to contact Notts Police on 101.
Advice on how to spot fakes is available from the Bank of England.