Police Scotland is warning people in Tayside to be on the alert for counterfeit Bank of Ireland £50 notes.
The fake cash is being used in the region and in Dumfries and Galloway, the Borders and Stirling.
Detective Inspector Iain McPhail said: “Suspects are using both an old-style £50 note which is green in colour and the newer note which is purple.
“Shops should only be accepting the newer purple note. If anyone is presented with a green old-style £50 note they should be declined and the customer informed to take them to their local bank.
“All genuine new-style purple sterling notes feature a watermark, a hologram that changes, a series of dashes which become a solid line when held up to light and the name of the bank in raised print.”