POLICE in Alcester are warning motorists following an increase in cars being stolen without the original key.

There are a number of ways the security can be bypassed or replicated by criminals.

One way is known as keyless or relay theft where offenders are stealing or purchasing relay amplifiers and relay transmitters and will then look for a suitable vehicle to steal.

One person will stand by the target car with the relay transmitter, while a second waves a relay amplifier around the perimeter of the building where they think the key is.

If the car key is close enough the amplifier will detect its signal, amplify it and send it to the transmitter.

This transmitter then effectively becomes the key, and tricks the car into thinking the real key is nearby, whereupon the thieves are able to open the car, get in and drive away.

The whole process can take as little as 60 seconds and can be completed in near silence.

Police have offered some advice to help prevent these crimes:

* Make sure the vehicle is locked in the first place. If possible use a secure garage or parking bay to store the vehicle out of sight.

* Keep keys secure and far away from the vehicle as possible.

* Put keys in a 'faraday pouch'. This will block the signal from the key to the car.

* Use steering wheel locks, parking posts and wheel clamps.

* Check with your manufacturer to see of the key fob can be turned off when not needed.

* Fit aftermarket electronic immobilisers and trackers.

* Use motion activated lights and CCTV to cover your car and building boundary.

* Report any suspicious activity in your area to police on 101.