In addition to the serial number, the fake notes can also be identified by their non-existent metallic vertical strip.
Pictured: A fake bank note would have the serial number F06878 in the bottom right-hand corner.
Anyone who comes into possession of a counterfeit note is asked to hand it to Guernsey Police to help them trace the source.
Anyone with information regarding the fake bank notes is asked to contact PC 29 GEDDES on 222222, email Peter.Geddes@guernsey.pnn.police.uk, or contact Crimestoppers anonymously on 0800 555 111.