Police are appealing for residents to be on their guard after a series of thefts by people claiming to be from water companies.

This month police have had reports of about 20 distraction burglaries most of which have been in the Bristol area. The offenders are visiting houses and getting in by telling the occupant that they need to check the water pressure. Victims are asked to turn taps on and off in order to keep them busy while a second offender searches the house.

In one incident, a man had called at a house in St George.

The victim, an elderly woman, let the men in and was running the taps when she heard a noise upstairs.

When she questioned it she was told by the offender it was one of his colleagues and she thought he must have been checking the upstairs taps. Later it was discovered the money had been taken from two purses.

Police are appealing for information about the men committing these offences and the vehicles they are using. Anyone who receives callers they believe to be suspicious should make a note of their description and any vehicles they used, especially the number plate.

Bristol Water officials carry identification cards which include a name, photograph and logo and will be shown to residents.

Bristol Water customers can also register a secret password with the company which genuine officials must give in order to be admitted.

Anyone who is not sure whether someone on the doorstep is genuinely from Bristol Water should ring freephone 0800 373 501 to check the caller's identity.

Bristol Water is offering a £4,000 reward for information in connection with people committing offences while posing as Bristol Water officials - for more information visit www.bristol-water.co.uk.

Detective Sergeant Janice Pearson, from the Doorstep Crime Team said: "The criminals committing these crimes are callous and have a complete disregard for their victims and the long-lasting impact of their actions.

"We are determined to identify the people responsible and anyone with information about the men committing these offences should come forward.

"Bristol residents can help us tackle the problem by reporting any suspicious visitors calling on people in their area. "Please keep a pen and paper by the door and, if you are concerned about someone in your street, make a note of their description, any vehicle they use and the direction they leave in and let the police know.

""While there has been a spate of these offences recently residents should not be unduly worried.

"To protect yourself against distraction burglary don't open the door to unknown and unexpected callers. Take steps to establish that they are who they say they are and only let them in once you are completely sure.

"Always ask for identification and, if in doubt, ring up the company using the number in the telephone directory not any number on an ID card.

"If you are concerned about someone currently in your area call 999 immediately. If they have left the area, or you have other information which could help please call Avon and Somerset Constabulary on 0845 456 7000."