Homeowners are warned to be on their guard against a technique burglars use to scout vulnerable properties.

Police have received reports that stickers are being placed on doors or letterboxes of houses advertising a locksmith service.

The sticker has a telephone number on it, but the number is not registered.

If the stickers are not removed, burglars presume that the house is empty or that the owners are away.

Placing the stickers also gives burglars the opportunity to inspect the house by looking through windows and, if confronted, say they are delivering advertising.

Police are now asking that homeowners keep an eye out for – and to report - any suspicious activity to ensure that burglars are thwarted before they get a chance to strike.

DCI Neil Parker from Kent Police said: “At Christmas time people tend to have some high value and new items in the house that are appealing to burglars.

“That is why we are asking members of the public to keep an eye out for unusual signs that might suggest the house has been ‘marked’ as a possible target and to report anything suspicious to us.

“It is well worth homeowners investing in items such as timer switches for lights and alarms for sheds.”