Counterfeit cash used at three food stores in Dickson

Businesses have been urged to be on the look out for counterfeit money after fake $100 notes were used at three separate stores in Canberra's north.

The counterfeit notes were used to buy goods at food businesses in Dickson on Friday.

An ACT Policing spokesman said shop owners should ask staff to be careful when accepting large denominations like $50 and $100 notes, taking the time to look over all money.

He said there were several telltale signs for imitation money, but if a business owner was unsure they should refuse to accept suspicious notes.

"Traditionally, they're just a touch smaller and they do have a different feel," he said.

"We're asking all store keepers and staff to be vigilant ... have a look at it, have a feel of it."

The spokesman said a counterfeit detection guide was available for businesses on the Reserve Bank of Australia's website.

Police were unable to identify the businesses given the fake money as investigations were still underway.

"CCTV is one line of inquiry we do have open to us," the spokesman said.

Officers have asked store owners to report all attempts to pass counterfeit currency to police on 131 444.