AGGRESSIVE salesmen are using sneaky tactics to trick vulnerable householders into switching electricity and gas providers.

Now, Ealing Trading Standards, alarmed by the sales techniques, is warning pensioners to beware of utilities companies cold calling at their homes and luring them into providing a signature which effectively opens an account often requiring a start-up fee.

Councillors last week heard reports of residents' complaints of door-to-door sales representatives inducing them into signing contracts with companies by stating that they require a signature to prove to their boss that a particular address was visited. Others complained that agents had told them a signature was needed to confirm that the householder has been notified of a gas leak.

Door-to-door salesmen not acting for any company but calling themselves 'brokers' have also appeared, charging residents up to £40 to shop around for the best utilities price and then disappearing with the money.

Trading Standards Service head, Helen Wilkie, said: "Elderly residents should take extreme care. It can be a confusing marketplace as there is a pile of information on different charging systems with which to muddle a potential buyer. Our message is do not buy anything, sign anything or engage with anybody at the doorstep that you weren't expecting."

And Hugh Lowe, spokesman for Ealing Borough Senior Citizens' Action Group, said: "Because the majority of elderly people are poor, they are anxious to save even the smallest amounts of money. This makes them easy prey for a salesman offering to save them £30 a year on their gas bill but it's only later they discover they've been tricked.

"Marketing is constantly getting more aggressive. Telephone and house calls are more frequent."

Call Energywatch on 0845 906 0708 for gas enquiries and 0845 601 3131 for electricity.