FAKE £50 notes are being circulated in Blackburn.
Traders have reported the counterfeit cash being used in their stores to make purchases, prompting a police investigation.
One of the latest businesses to become a victim was The E-Cig Shop, in Limbrick, whose manager Annis Mangera said smaller companies were being put under strain by the use of fake notes.
Officers have now released CCTV images of a man they would like to speak to in connection with the frauds at the Limbrick store.
Father-of-two Mr Mangera said his shop assistant was tricked into believing the notes were real by a man who used a £50 to buy an electronic cigarette. He was given £40 in change, but then said he needed to buy some fluid, which he tried to pay for with a £20 note, Mr Mangera said.
When the worker challenged the man about the money, which the manager said was obviously fake, the fraudster pulled out another £50 to pay for the item, before leaving the shop.
Mr Mangera said: “The same guy came into the shop a few days beforehand, I suppose to suss the place out.
“The next time he came in, he said he had just got the notes from the bank and my shop assistant did notice that he had about 10 of them in his wallet. I am a small trader, I am not worth millions. You can take an occasional hit if you are a bigger business, but when you only on average make £100 a day, it does annoy you.
“I am a working man and I just want to make my living legally and feed my family.”
The man officers believe might be able to help them with their inquiries was described as being Asian, with very short black hair and in his mid to late 20s.
PC Anna Gavela, from Lancashire Police’s planned response unit, appealed for anybody with information about the counterfeit money or anybody who knew the man to come forward.
She said: “The man apparently had a large bundle of these notes so has very possibly passed them in other shops.
“This may not be connected, however it does look like there are quite a lot of these notes in circulation and it would be interesting to know if they are coming from the same source.”
Anybody with information should call police on 101 or Crimestoppers anonymously on 0800 555111.