Police are hunting a group of teenagers who allegedly used counterfeit $50 notes in shops at Civic and Dickson on Tuesday.
The fake bank notes were first used at a convenience store in Civic about 6.20pm, police say.
The four teenage boys, aged between 16 and 18, walked into the store and asked for a $50 note to be swapped for change.
The owner didn't notice the counterfeit note at first, and handed over the money.
He quickly realised and challenged the teenagers, who police say fled from the store.
A short time later, three of the teenagers walked into a Dickson supermarket, and again tried to use a counterfeit note.
The supermarket owner realised the bank note as a fake, and refused to accept it.
ACT Policing say counterfeit money is not common in the territory, but are urging Canberrans to be wary of dodgy bank notes.
North District Superintendent Brett Kidner urged shop owners to check money carefully, looking on notes for markings that prove their legitimacy.
“At the end of the day, if you're not satisfied that the note is legitimate then don't accept it," Superintendent Kidner said.
"When a $50 note is held to light, a seven-pointed star within a circle is formed by four points on one side of the banknote, combining perfectly with three points on the other side."
Police are still looking for the teenagers, and are urging anyone with information to come forward.
The three teenagers who entered the Dickson supermarket were all between 16 and 18, and were described by police as Aboriginal or Torres Strait Islander in appearance.
One was wearing a white hooded jumper, dark-coloured tracksuit pants, with a black backpack.
Another wore a dark grey T-shirt with a motif on the front, and blue coloured pants.
The third teenager wore a white T-shirt with a black motif on the front, blue pants, and a black backpack.
Anyone with information should contact Crime Stoppers on 1800 333 000, or at the website.