Fake copies of the new £5 pound note had been found in circulation in the UK, despite claims that the currency was almost impossible to forge.
The Bank of England has ordered an investigation after admitting that there had been cases of the design being passed off on paper. Police have also issued warnings about fake notes being in circulation.
The new polymer format which was introduced last year was considered impossible to counterfeit.
Since the new notes officially entered circulation in September 2016, they had been touted by the bank as "harder to counterfeit than paper notes".
The bank said on Friday it was unaware of any forgeries of the new polymer £5 note, though it added that the note's design had been crudely copied on to paper in a very small number of cases.
Aaccording to The Daily Mail people who might be worried they had counterfeit notes need to check the following:
- Check the see-through window and the portrait of the Queen.
- Check the Elizabeth Tower (Big Ben) is gold on the front of the note and silver on the back.
- Check the foil patch below the see-through window changes from 'Five' to 'Pounds' when the note is tilted.
- Check the coronation crown appears 3D (wiggle the note to see the effect).
- Check the ultra-violet feature (a '5' will appear at the bottom left when a UV light is shone on it).
- Check the circular green foil patch on the back of the note which contains the word BLENHEIM - after Blenheim Palace, the birthplace of Sir Winston Churchill who appears on the note.