Plastic $100 bills with complicated designs and holograms were supposed to be tough to copy — but that hasn't stopped counterfeiters from trying.

The Regina Police Service says fake $100s and $50s in the new polymer series have been passed to a variety of businesses in Regina and the surrounding area.

It's telling people and businesses to check their polymer money to see if the bills are fake.

Here's how the police service says people can check:

The large transparent window on the new bills contains small numbers. The small numbers in this window should match the amount of the denomination (100s if it's a $100 bill etc.).

The transparent window should feel smooth with the rest of the bill.

The counterfeit money that has recently been passed does not have the small numbers in the window matching the denomination of the bill. As well, the counterfeit window has tape on it, police say.

Businesses are asked to contact 911 if they get one of these bills.

They can also call the Regina Police Service at 777-6500 or Crime Stoppers at 1-800-222-8477.