Counterfeit nautical charts are posing a threat to safety, according to the UK Hydrographic Office (UKHO).
The UKHO says it has been alarmed by an increase in the number of counterfeit charts in circulation that have not been issued by a government or authorised hydrographic office.
UKHO marketing head John Dawson said: “Because counterfeit versions have not been through the same rigorous checking procedures as official admiralty charts and publications, they cannot be trusted for voyage planning or navigational purposes.”
The UKHO has provided simple guidelines to help distinguish between real and counterfeit charts.
“We also encourage anyone who suspects they may be in possession of counterfeit products to get in touch with us,” Dawson added.