North Wales Police arrested six men from the Bradford area on suspicion of fraud by misrepresentation.
The men are suspected of using counterfeit £20 sterling notes in fraudulent transactions across the coastal areas of Conwy and Denbighshire.
Detective Sergeant Dean Jones said:
“We are keen to hear from business people who suspect they may have been the subject of fraudulent transactions.”
Anyone who may have information relating to counterfeit banknotes is asked to contact St Asaph CID on 101. Alternatively contact the webchat http://www.north-wales.police.uk/contact/chat-support.aspx, or Crimestoppers on 0800 555111.