Poverty is driving many older people to risk their health by skipping meals to save money, according to Age Concern and Help the Aged.
A report by the newly-merged charity warns that the economic downturn is forcing many older people into an ever-tighter financial corner.
Says the group's charity director Michelle Mitchell: "Many are being clobbered by high prices and are being pushed to extreme measures to cope financially. The government cannot sit by while older people skip meals and put their health at risk. The oldest and poorest pensioners are being hit particularly hard.
"The state of the economy is the defining issue of our times and this year's Budget will have many demands on it, but the challenge to Government is to ensure that older people, and older voters, aren't forgotten. Investment to stimulate the economy must also benefit them."
He said that a much higher than average relative inflation rate means that pensioners on low incomes are struggling to afford food, electricity and other basic household essentials.
One in five are being forced to buy less food, while two-fifths are cutting back on socialising, electricity and gas, he said.