Homeowners could see their energy bills rise even further over the next ten years, it has been predicted.

New figures from Which? show as many as four million households could be in fuel poverty by 2010 if people do not make their homes more energy efficient.

Failure to install insulation could mean that utility bills rise by over a third, Which? found, creating further problems for already strained household budgets.

"Energy is going to get a lot more expensive over the next decade so the only way to avoid bigger bills is to use less of it," said Which? editor Martyn Hocking.

The research predicted that the average energy bill for a three-bedroom semi-detached property could exceed £2,600 over the next decade.

Meanwhile, a detached family home could see its bills coming in at around £4,000.

"The government must take urgent action to stop bills from spiralling out of control and to help consumers make their homes more energy efficient, otherwise millions of people will be faced with crippling energy bills in the future," said Mr Hocking.

Costs will rise as a result of the wholesale price of energy rising, Which? suggested, with an increasing dependence on imported energy also playing a role.

Not everyone will be able to foot the bill for rising utility bills, the consumer website found, as 73 per cent of people questioned said they would worry about the affordability of increased costs.

Furthermore, research showed that 28 per cent of homeowners are already concerned about being able to afford their utility bills.

Earlier this week, the government announced plans to make it easier for people to understand how eco-friendly their homes are.

Housing and planning minister John Healey pledged to clarify the existing Code for Sustainable Homes to make the proposals more transparent for consumers.