Domestic fuel bills are set to rise by at least 50% when the new energy price cap comes into force in April, warned Money Saving Expert founder Martin Lewis as he called for intervention from the government to avoid a crisis in the energy market.
"What's coming in April is a seismic hit for fuel bills which is going to be astronomical," Lewis told PA news agency.
"They [the government] have to sort this now because if we leave this before it's too late it will be a disaster."
READ: UK energy industry urges government action as domestic bills set to soar
The government's energy price cap is due to be revised in February, with an increase applied to households’ energy bills from April.
"We are going to see a minimum 50% increase in energy prices in the system and that is unsustainable for many," Lewis warned.
The current price cap of £1,277 a year could rise by 46% to £1,865 a year from April, according to energy sector specialist Cornwall Insights.
This could increase further to £2,240 in the autumn of this year if global energy prices remain high, the firm said.
"We need to look at what we can do now and how we can protect those people who will need to choose between heating and eating," Lewis said.
He called for greater protection for the most vulnerable consumers, who may not be able to shop around for the best deals, or are stuck on expensive pre-payment options.
A large number of UK retail energy suppliers folded last year because the energy price cap prevented them from passing higher costs on to their customers.
Energy suppliers that took on the customers of the collapsed suppliers will be able to claim back more than £1.8bn by adding it to the bills of households and businesses, putting further pressure on domestic bills.
”The government didn't intervene early enough so we're all paying for the market collapses we're seeing," Lewis said.
A government spokesperson told Sky News: "Protecting consumers is our top priority which is why our energy price cap will remain in place.
"We are also supporting vulnerable and low-income households further through initiatives such as the £500mln household support fund, warm home discount, winter fuel payments and cold weather payments.
"Domestic fuels such as gas and electricity are also already subject to the reduced rate of 5% of VAT."