Labour leader, to propose freezing the energy price cap this autumn as part of a cost-of-living plan.
Sir Keir Starmer is expected to make the decision on Monday, and to explain how Labour would fund the plan if it were in power.
The cap is £1,971 per year, which is the maximum amount suppliers can charge customers in England, Scotland, and Wales.
However, experts predict that it will rise to around £3,500 per year, with steep increases in bills for every household.
Previously, the cap level was only reviewed every six months, but Ofgem changed the rules this year, so it is expected to rise in both October and January.
The government has already announced that all households in England, Scotland, and Wales will receive £400 to help with rising fuel bills this autumn.
Sir Keir wants to end the ‘injustice’ of prepayment meters paying over the odds for energy. Labour would also impose a windfall tax on oil and gas firms, Sir Keir said.
