MPs have been warned by chief of Ofgem Johnathan Brearley that the energy price cap will rise in October from £1,971 to £2,800.
During the Business, Energy and Industrial Strategy Committee meeting on 24 March, Brearley told MPs the figure was provisional but based on the most accurate current estimates.
The price cap is estimated to raise the average annual bill by more than £800 and comes not long after the cap increase of £693 in April.
Independent think tank the Resolution Foundation has said that 9.6 million families across the country will experience more energy bill stress this winter.
The Government has been under pressure from many to do more about the rising costs of living, with inflation hitting a 40-year-high of 9% this year.
Jonny Marshall, senior economist at the Resolution Foundation, said:
"UK households are set for another huge jump in the energy bills this October - just when the need to heat their homes grows.
"The sheer scale and depth of Britain's cost-of-living crisis means the Government must urgently provide significant additional support."
Marshall continued: "households will also benefit most from cheaper renewable energy and lower consumption from better insulated homes - showing why Britain needs to step up its retrofitting programme."
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