People in Norfolk have been warned to "be on their guard" against door-to-door scammers following a spate of incidents.

The county council's trading standards department issued the warning after receiving reports of rogue traders in the Long Stratton area who were offering to sharpen machine tools and blades.

It said of one incident: "A business was approached by a smartly dressed young male who presented himself as very knowledgeable about this type of work and initially offered to sharpen a small number of blades 'free of charge' to show the standard of their work.

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"When the tools were returned by the young man, another man was there to pressure the business to agree to further work. 

"Often there is no initial quote provided for the service and the price will increase dramatically upon return making the business feel compelled to pay to get their items back."

The department said to never deal with cold callers who arrive unannounced with offers of work or items for sale and that these traders may move on to other locations within Norfolk.

They are believed to be using more than one small white van displaying non-UK number plates.