Waterloo Regional Police say there's an increase in the number of counterfeit U.S. banknotes given to stores in the region.

Det. Const. James Gordon, who is with the fraud branch, said the bills are popping up at retailers in Cambridge and Kitchener.

"We've noticed a recent increase in the number of primarily $50 American banknotes," said Gordon. "We've also had a few incidents with counterfeited $100 bills."

Stores and retailers are allowed to accept U.S. cash for goods and services if they decide to do so. Gordon said the counterfeits are generally reported to police by store managers or detected when they are taken to a bank.

"The American banknotes for the most part, the security features are similar to Canadian banknotes," said Gordon. "However, the retailers, some of them just don't receive as many of them so they don't know what particular security features to look for."

Gordon said if anyone comes across currency they believe to be counterfeit, they should inform police.