Residents are being warned to be on their guard against thieves posing a water and gas company officials.

Thames Valley Police, British Gas and Thames Water have joined forces to warn people in Oxford to watch out for bogus callers. The warning comes after reports of people answering the door to callers posing as water and gas supply officials.

On Thursday, a bogus water offical asked a householder to turn off his supply, but the resident refused to allow him in and he left immediately.

This caller was white, in his 20s, about 5ft 8in with curly hair. He wore beige trousers and a checked shirt or jacket.

Fifteen minutes later, £100 was stolen from a 76-year-old woman by three men posing as gas officials.

One wore a checked shirt, another was about 6ft tall and wore a white sweatshirt, and the other was wearing a dark blue jacket.

Police, British Gas, and Thames Water are urging residents to:

**Be prepared. Have a door chain or spy hole fitted

**Ensure you know what to say and do when someone unexpected calls

**Secure your door chain before opening the door

**Ask all suspicious callers for identification and keep the door chain on while you check it

**Feel confident in being able to say no if someone wants to come in without showing their ID

**Feel safe rather than sorry. If you are suspicious, do not let them in; if you are worried, call the police.

Thames Water's head of customer services Barbara Moir said: "Callers from Thames Water, or our contractors, Subterra, will have an identification card, which should be carefully checked. If in any doubt, people should ring our customer care centre to confirm the details.

"Callers genuinely representing the company will be happy to wait."

British Gas area manager Derek Carr added: "All British Gas representatives and contractors working on behalf of British Gas carry an identity card with a photo on it which customers should always ask to see."

Call Oxford police on 01865 266333 if you any suspicions about a caller.