Ofgem has warned it is likely to rise to £2,800 from the current cap of £1,971 in October.
It comes as a charity warned the hike will plunge households into a ‘deep, deep crisis’.
Ofgem chief executive Jonathan Brearley told MPs the regulator is expecting an energy price cap in October ‘in the region of £2,800’ as the market copes with ‘once-in-a-generation’ price changes ‘not seen since the oil crisis of the 1970s’.
Energy prices pushed the consumer prices index (CPI) to 9 per cent in April, and Mr Brearley’s remarks immediately led to calls for the Government to do more to help households cope with the deepening cost-of-living crisis.
Adam Scorer, chief executive of National Energy Action, said: ‘Ofgem’s warning that the price cap will rise again by over £800 in October will strike terror into the hearts of millions of people already unable to heat and power their homes.
‘It will plunge households into deep, deep crisis. The financial, social and health impacts are unthinkable.
‘The UK Government simply must act and use the welfare system and schemes such as Warm Homes Discount to get significant financial support to people before winter. The ambition should be to find ways of covering the entire price increase for people on the lowest incomes.’
Ofgem’s prediction is a further 42 per cent hike on April’s price cap increase of 54 per cent, or an increase of £693 a year to £1,971 for those on default tariffs paying by direct debit for the average household.