RESIDENTS are being warned to be on their guard against a doorstep scam in which crooks pose as police officers.

The ruse involves conmen who claim to be from the police’s crime prevention department knocking on doors and offering to sell burglar alarms for �1 each – however, the upkeep costs are said to be “huge”.

To date, police have had a “number of calls” about the wheeze, all from the Brookmans Park area.

PCSO Louise Luxford, from the Brookmans Park and Little Heath Safer Neighbourhood Team, said: “Police will NEVER call on you and try to sell you products. Should you receive such a call then please do not give any details to the caller.”

A police spokeswoman added: “Genuine police officers will not need this information.”