Analysts have warned that householders' energy bills may soar by up to a fifth in the New Year as suppliers pass on a rise in wholesale gas prices. Russian firm Gazprom, which is responsible for supplying a quarter of Europe's gas, said that it expects suppliers to raise charges by February 2008.

Karen Darby from SimplySwitch, the price comparison and switching service, said: "Wholesale prices have been creeping up for some time now and several analysts are predicting gas bills to rise by at least 15 per cent.

"Almost three quarters of UK homes are connected to the gas mains, so this will affect millions of people directly. However, it's not just gas bills that are likely to soar. With 40 per cent of the UK's electricity generated by burning gas, a rise in wholesale gas prices means that electricity bills will rise too.

"Over the past year, wholesale gas prices have fallen by half, with wholesale electricity costs down by almost a third. Despite some highly-publicised price reductions, the major suppliers have only brought average bills down by around 15 to 20 per cent. If energy prices rise as much as analysts are predicting, customers could be forced to pay an extra £131 per year in energy bills.

"It has already been estimated that an energy price hike of just 10 per cent would push 400,000 more households into fuel poverty. A rise of 15 to 20 per cent would have an even more devastating effect, and more needs to be done to protect vulnerable households. "