Energy campaigners say millions more families are now spending an unsustainable share of their income on household bills
Millions of British households are facing significantly higher energy costs after the Government's energy price cap rose to £1,862 annually.
The increase of more than £220 marks the steepest summer rise in four years and follows months of turbulence in global gas markets.
Fuel poverty campaigners warn the consequences are severe, with an estimated 13.5 million homes across Great Britain now spending more than a tenth of their income on energy, up from approximately 11.3 million in April.
The figures, calculated by the End Fuel Poverty Coalition using research from the University of York, highlight the growing pressure on families already struggling with the cost of living.
Under the regulator's revised methodology, which assumes lower household energy consumption, typical annual spending is estimated at £1,663.
For households paying by direct debit, electricity charges have increased from 24.67p to 26.11p per kilowatt hour, while gas prices have risen from 5.74p to 7.33p.
The coalition's analysis also found that nearly 5.5 million households are now spending around a fifth of their income on energy bills, up from 4.3 million three months ago.
Simon Francis, the coalition's coordinator, said: "These figures show the reality behind the headline price cap figure: a growing number of households are spending an unsustainable share of their income just to heat their homes in winter and keep them cool in summer".
Mr Francis said households are unlikely to rebuild their finances before colder weather arrives.
He said: "With energy costs rising over the summer, any chance households had to reduce energy debts or build up reserves before the winter heating season will be wiped out".
The rise in costs has prompted Unite to organise demonstrations across the country calling for significant cuts to energy prices and the return of energy companies to public ownership.
Sharon Graham, the union's general secretary, said: "The increase in the energy cap is another kick in the teeth for workers and families who were already struggling with ever-rising bills and the cost-of-living crisis.
'The UK has among the highest energy bills in Europe, they should be going down, not up."
Energy analysts at Cornwall Insight have suggested there may be only limited relief later this year.
Their forecasts indicate annual bills could fall to around £1,654 from October under the regulator's updated methodology, representing a reduction of just 0.5 per cent from current levels.
Meanwhile, Andy Burnham, the Labour MP widely anticipated to become the next prime minister, outlined plans to devolve control of essential services, including energy, to local leaders during his first major public address on Monday.
Responding to those proposals, Mr Francis said any reforms would need to be accompanied by broader changes to the energy market.
He said: "Plans to devolve control of energy will count for nothing unless they are accompanied by a permanent social tariff, an end to energy debt, reduction of electricity costs and a credible plan to break the link between gas and electricity prices".
Martin McCluskey, the minister for energy consumers, said: "We know families are deeply concerned about rising energy bills because of a war we did not choose, and we are determined to fight their corner to tackle energy affordability".
The Government said it has removed certain policy costs from household energy bills and expanded its Warm Home Discount scheme to support six million homes.