Residents across the county are being warned to be on their guard following reports of traders attempting to sell what is believed to be substandard fish door-to-door.

Norfolk County Council's trading standards team has received a report of traders calling unannounced to a business in central Norfolk and attempting to sell fish.

They believe the traders may move on to Norwich, Lingwood, Blofield and Acle and surrounding areas, targeting homes owned by more vulnerable members of the community.

The traders, who use an unbranded non-refrigerated van, are reported to use high pressure sales tactics.

Trading standards officers also have doubts about the quality of the fish being offered for sale, whether the type of fish is as claimed and if it has been appropriately stored.

Stephen Maunder, for Norfolk Trading Standards, said: 'If these traders knock at your door, we would certainly suggest that you do not buy any fish from them, and consider not opening the door to them.

'We would urge members of the public to buy from one of the many reputable fish merchants we have here in Norfolk because you can be sure of the type and quality of the fish on sale; they are, without doubt, a much better alternative to buying fish from somebody arriving at your doorstep unannounced.'

Trading standards officers and police issued a number of warnings about doorstep fish sellers in 2008 and 2009.

In once instance in 2009, traders called at the home of one vulnerable man in Norwich and convinced him to buy 65 packs of fish for �900. However, the fish was only worth around �150.

For more information on doorstep selling and how to stay safe, telephone the Citizen's Advice consumer helpline on 08454 04 05 06.