As British consumers were hit with yet more crippling rises in their fuel bills, the Tories unveiled a plan which they said could help Britain’s poorest households reduce their energy bills by £100 a year.

They are targeting more than four million families who have accounts with the Post Office and therefore cannot benefit from lower energy and water tariffs offered to customers paying their bills by direct debit.

The Tories say they will reform post office accounts so that for the first time they can be used to pay utility bills using the equivalent of a direct debit.

Shadow Chancellor George Osborne said: “It is deeply unfair that many of the poorest households end up paying more for their energy and water bills because they don’t have bank accounts and can’t pay by direct debit”.

Mr Osborne said that the Conservatives had the backing of EDF, the French power giant, United Utilities and Water UK, the body that represents the UK’s water companies.

For every one of their post office customers who agrees to switch over to paying by direct debit, the energy companies will pay the Post Office a fee of between £5 and £10 for administering the service.

Not paying bills by direct debit adds a substantial penalty onto household bills because of the higher collection costs faced by energy companies dealing with customers without bank accounts.

It is estimated that direct debit customers save up to £80 a year over standard customers, such as those with post office accounts, according to Energywatch.

As well helping to fund the plan, the Tories reckon the fees will generate enough money that the Post Office could have a surplus of about £20 million a year. The funds “could help keep some Post Offices from going to the wall as a result of Labour cuts”, the Tories said.

Mike O’Brien, the Minister for Pensions in the Department for Work and Pensions, which oversees post office accounts, was quick to dismiss the Tories’ plan, saying that while there are 4 million people with Post Office accounts, about 3 million of them already have building society or bank accounts and therefore have access to direct debit facilities if they wanted to take advantage of them.

He added that post office accounts are only available to people on benefits and one of the key aims of the government is to help people off benefits and into work.

He said: “Having a bank account is an integral part of being ready for work so there is little point in making people more dependent on an account which can only be used when they are on benefits”.

Times Recommends

• ‘Lame duck’ fear for FSA as chief quits
• Storm over bailout of EU's most ailing economy
• Northern Rock to drop 100% savings guarantee