Elderly residents should "be on their guard" this Christmas when answering the door to cold-calling bogus traders, warn police.

The police advice comes as an operation has been launched to identify and prosecute those who have targeted pensioners in the Colchester and Clacton areas during recent months.

Detectives suspect many have fallen foul of "predatory" salesmen, who have taken money for "poor quality work” on building work, roofing, gardening and general household repairs. Officers believe the impact that bogus or persistent doorstep rogue traders have had on people can far outweigh any financial loss or property damage, with dramatic effects on the quality of life.

David Gillies, Crime Reduction and tactical advisor, said: "A wide range of goods and services are sold to people in their own home.

"It can be convenient to buy on the doorstep and many of the traders are honest and genuine. "However, with the use of clever sales tactics it can be difficult to refuse some sales people and you can be pressured into buying something that is not good value for money."

Doorstep traders should always be asked for identification and should not be dismissed as genuine salesmen. Many of the businesses operating across Essex offer a good, reliable service however there are occasions when traders are not always who they say they are.

For more information and advice, call Essex County Council Trading Standards on 08454 040506 or find a trading standards-approved trader at www.buywithconfidence.gov.uk Anyone with information in connection with a rogue trader or has been visited by one should contact Essex Police on 101 or 999.