The poll by the charity shows a sharp rise in concern over energy bills just weeks before the widely anticipated price cap announcement from Ofgem.

More than half (52%) of over-65s – 6.5 million older people – are worried about their energy bills now compared to just under a third (31%) last month. Nearly half (45%) are worried about having to reduce energy use due to financial concerns compared to less than a third (30%) in December.

The survey also found that 82% of over-65s think the government should step in to help poorer older people pay their energy bills.

The high levels of concern are reflected in a surge of support for Age UK this month, with more than 50,000 people adding their names to a letter to the prime minister in the past week, urging him to act now to protect older people from unaffordable energy bills.

Age UK is warning that many older people are already feeling the impact of the rising cost of living, with basic household bills fast becoming unaffordable for many pensioners living on a low fixed income.

With the latest projections suggesting that the energy price cap will nearly double to £2,400 a year from October, Age UK is deeply concerned that this colossal rise is likely to push tens of thousands more older people into fuel poverty and force huge numbers to start rationing their heating.

Age UK has been flooded with stories from thousands of older people who are already struggling and cutting back on heating, food and other essentials.

The charity says financial support for older people during the colder months has remained broadly unchanged for years and is nowhere near enough to match the scale of the current problem. In its letter to the government last week, Age UK urged ministers to announce a financial package to support vulnerable older people through this crisis.

The charity is calling for VAT to be reduced from energy bills until at least the end of 2022 and also for support payments of up to £500 to be given to older people on the lowest incomes.

Caroline Abrahams, charity director at Age UK, said: “The number of older people who are worried about being able to heat their homes is staggering and should be a source of shame for this government. Millions of older people across the UK are absolutely dreading the imminent price cap announcement and urgently need reassurance that help is on its way so they can keep their heating on. This is a national crisis which needs a swift and decisive response from ministers.

“Every single day we are hearing heart-breaking stories from desperate older people who are being forced to choose between heating and eating. This isn’t a looming crisis, it’s already upon us – and while the government is dithering, millions of older people are suffering and putting their health at risk because they can’t afford to keep warm. It is an absolute scandal and one that requires urgent government action.

“Energy price rises on the scale we are now seeing are unprecedented and the government’s response must be equal to the threat they pose to older people, many of whom are vulnerable and struggling to afford exorbitant bills on a meagre state pension.”