Energy chiefs will be asked to defend expected future rises in fuel bills when they appear before MPs today. Domestic suppliers are under pressure to justify pricing expectations after it was discovered household energy bills could rise by up to 40 percent this winter.

Industry experts have suggested that households could pay up to £400 more a year for gas and electricity. Suppliers are said to be reacting to the sharp jump in wholesale gas costs, triggered by rising oil prices.

Wholesale gas prices are closely linked to the price of oil, which itself has recently hit just under $140 a barrel.

Industry research has suggested wholesale gas prices have risen by more than 70 percent in 2008. Last month Centrica – who own the UK’s biggest energy provider, British Gas – signalled that gas prices for customers are likely to increase again later this year.

Centrica’s chief executive Same Laidlaw will appear before the Commons Business and Enterprise Select Committee today, along with other senior industry figures.

MPs want to find out what suppliers expect to happen to fuel bills over the winter. They will also press energy chiefs on the extra help being given to low-income and disadvantaged households to help with the impact of rising bills.

Watchdog, Ofgem, who are conducting their own probe in to the market, outlined plans last month to share data about people on low incomes with the energy companies to help people pay their fuel bills. The proposals, which would need to be approved by parliament, are designed to ensure that financial assistance toward fuel payments can be better targeted at the elderly and vulnerable.

The government has estimated that 2.5 million UK households are suffering from fuel poverty – defined as when more than 10 percent of household income is spent on fuel bills – but watchdog Energywatch says that the figure is over four million.

A 40 percent rise in fuel bills would be far higher than expected and would put even more pressure on homeowners already struggling with higher food and fuel costs. However, some analysts believe the increases will be nearer to 25 percent.

It is believed any price announcements will come in August, when energy bills are not at the forefront of people’s minds. It is thought, however, that there is reluctance in the industry to be the first company to reveal a big rise, so they could be unveiled in stages.

Involved in the meeting today are the chief executives of Scottish & Southern Energy, NPower, EDF Energy and E.ON UK. A representative of Scottish Power will also be present.