Police want householders to be on their guard against door-to-door burglar-alarm salesmen.

PC Adrian Foyston, Keighley's crime reduction officer, said the technique, plus neighbourhood leafleting, was often carried out by people with little knowledge of the security business.

He has received an increased number of calls from the public on the issue.

He said: "There is a growing trend for leaflet dropping an area or even door knocking, often leading to a high-pressure sales visit. These techniques are undertaken by people purporting to be experts in the security business, when in fact they have little knowledge or credibility in this specialist field.

"You should never allow anyone into your home to survey your current security levels who you do not know, has not been recommended to you by someone you can trust and who you have not invited to your address. Please remember, if in doubt, keep 'em out."

Advice relating to burglar alarms can be obtained from your local crime reduction officer on 0845 6060606.