Money Saving Expert founder Martin Lewis has urged the Chancellor Jeremy Hunt to postpone April's increase in energy bills.
The consumer champion described the planned hike as a “national act of harm” which could plunge another 1.7million into fuel poverty in the coming months.
In a letter to the Chancellor he said the increase was no longer necessary because wholesale prices have "come down very substantially".
He added: "Postponing the increase is a practical and fair decision, with household energy bills already double what they were the prior winter.
“Crucially the damage to people’s pockets and mental health of another round of energy price rise letters is disproportionate."
Under the Government's "energy price guarantee" typical bills are frozen at an average of £2,500 - but will soon become less generous.
In November the Chancellor Jeremy Hunt announced the cap will be increased to £3,000 for the average household in April.
There are also no plans by the Government to extend a £400 payment made available to all households across the country this winter.
But speaking on BBC Radio 4’s Today programme Mr Lewis said: “The nation is already shivering with the damage of the cost-of-living crisis and it just seems to me there is no need to do this.
“I would ask the Chancellor to postpone this rise”.
He added: "To put this national act of harm of increasing the price guarantee for just three months, to throw another 1.7million people into fuel poverty taking it to 8.4 million, it seems unnecessary."
Mr Lewis said any cancellation would have to happen before the March Budget because by then people will have had letters telling them their bills are going up.
Describing energy prices as "effictively nationalised", he added: "This is the one price mechanism that is fully in the Government’s control and it is choosing to put it up on 1 April."
Labour's Shadow Chancellor Rachel Reeves said the personal finance expert "is right".
She added: "We need to stop bills going up in April.
" That's why Labour would freeze energy prices - paid for by extending the one-off tax on energy companies making windfall profits from war."
Last month Ms Reeves urged Rishi Sunak to cancel the rise in April as she accused the Prime Minister of "burying his head in the sand" as the cost of living soars.
She highlighted that many families are looking at a 40% increase in their bills, adding: "At the same time, energy companies continue to enjoy record profits. This cannot be right."
A Treasury spokesperson said: “Wholesale prices falling is good news, but as we have all seen, prices are volatile and can increase as fast as they fall.
"If prices return to their late August level, the government would need to borrow an extra £42 billion and potentially increase taxes to continue funding the Energy Price Guarantee at current levels."
They added: "The way the Energy Price Guarantee operates means households will still see lower bills if gas prices continue to fall. To support families in the meantime, we are providing millions of vulnerable households with £900 in direct cash payments this year, plus a record increase in the National Minimum Wage, and a 10% uplift in working-age benefits and the state pension.”
