Millions of older people in the United Kingdom cannot afford heating amid high energy prices, with experts predicting that energy bills could rise by up to 50% in the spring, the leading U.K. charity for older people, Age UK, warned on Thursday.

Soaring energy bills mean older people with low incomes are limiting heating and the use of hot water while living off soup and sandwiches to pay their increased energy bills, said Age UK, demanding immediate government action to prevent millions more falling into fuel poverty.

The 50% increase would bring average annual bills up by an additional 600 British pounds ($824).

Around 80% of pensioners, corresponding to around 930,000, say they could not afford an unexpected bill of 200 British pounds, the latest government figures show.

In light of these figures, the charity calls for immediate action to protect older people with the least ability to pay their bills.

"Rising inflation is already eating into the pensions of swathes of older people," the charity said in a letter written to the Secretaries of State for Business, Energy and Industrial Strategy and for Work and Pensions.

The charity is warning that "the unprecedented hike in wholesale energy prices will be totally unmanageable for those living on low fixed incomes, many of whom have few, if any, savings to fall back on."

"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," Age UK underlines.

It argues that mechanisms exist to fund vital support to see older people through this crisis.

Two suggestions for such mechanisms include cutting the 5% rate of VAT from all household's energy bills from April until at least the end of 2022 and providing additional support in payments of up to 500 British pounds to older people with the lowest income levels.