The public are being warned to be on the alert to the dangers of security companies whose sales representatives have been knocking on the doors of Brentwood homes.

They are worried that people may unwittingly give away all important details of their home security.

The warning was sounded by local Neighbourhood Watch groups after several householders reported that "representatives" from security firms had called at their homes asking questions about security measures.

Brentwood Crime Prevention Officer, Pc Victoria Wilson, said: ''Though we would always advise people to buy an alarm and good quality locks they should not do so from a stranger on the doorstep.

"No one should answer questions about their own home security if they are asked by someone who has just turned up on their doorstep.

"They may well be from bone-fide companies but you just cannot be sure who you are talking to.

"Luckily the local Neighbourhood Watch groups have cottoned on that this is happening so giving us the opportunity to issue an overall warning.

''If you want to buy an alarm you can always contact us for advice and always make sure the company you buy from is affiliated to a police approved inspectorate."

These include:

National Approval Council for Security Systems (NACOSS), Queensgate House, 14, Cookham Road, Maidenhead, Berkshire, SL6 8AJ, telephone 01628 637512.

Security Systems Alarms and Inspections Board, 70/71 Camden Street, North Shields, Tyne and Wear, NE30 1NH, telephone 0191 296 3242.

Alarms Inspectorate and Security Council Ltd, PO Box 153, Southport, Lancs, telephone, 10704 500897.

Integrity 2000, PO Box 2222, Brentwood, Essex, CM13 3HY, telephone 01277 262000.

Intruder Alarm Inspectorate, 45c Bank Street, Rawtenstall, Lancs, BB4 7QN, telephone 01706 210999.

Pc Wilson said: "All these have been checked out by the police and are known to be reputable companies."

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