POLICE are warning traders to be on their guard after a gang used fake notes at the Giant Party Shop in Victoria Road on Wednesday.
It was the latest in 30 reported incidents of fake notes being used in the county.
Since January there have been a series of offences across Wiltshire involving fake £50 notes and fake Scottish £20 notes at shops, pubs and hotels in Chippenham, Corsham, Trowbridge, Bradford on Avon, Devizes, Warminster, Westbury, Mere, Ludgershall, Amesbury and Salisbury.
Police believe at least six men and women are involved in the scams and that they could be working as part of a wider team.
Police are warning businesses to be aware and to ask their staff to be extra vigilant.
A spokesman said: “If anyone should try and use a fake note, please dial 999 immediately to give officers the opportunity to apprehend the offenders at the scene. If the offenders are no longer at the scene, then call Wiltshire Police on 101 or Crimestoppers on 0800 555 111 where information can be left anonymously.
“Please make a note of the offender’s physical description and also details of any vehicles that they are seen to be using.”
Anyone with information on the scams ca contact Alaina Coles in the Crime Management Unit on the police number 101, extension 728 341.