A Laverton clothing retailer is warning other traders to be wary after being given six counterfeit $50 banknotes.

Double C Jeanery retail assistant Ben Sydenham said a man had entered the Aviation Road store on July 24 and went to pay for two jackets and other clothing.

“He had a roll of notes and he just used them,” he said.

“When he handed them to me, you couldn’t tell. They just looked like new notes, they were fine.

“But when we had all the notes together doing cash-up [counting all the money at the end of the day] we could tell that they were fake.

“You’re meant to try to rip the note and this one didn’t rip, which is what the real ones don’t do.”

He also said the portraits of David Unaipon and Edith Cowan looked real but felt grainy.

The Reserve Bank of Australia advises people who come across a suspected counterfeit banknote to handle it as little as possible, store it in an envelope, note down any relevant information about it and report the matter to state or federal police.