Age UK revealed that 1.6 million UK pensioners are living in poverty, which is partly due to their failure to claim benefits.
According to the charity's report, called How We Can End Pensioner Poverty, over a million pensioners are living below the breadline as they have been "floundering" on low incomes and have failed to get the necessary financial help they are entitled to.
"It is nothing short of a scandal that there are still so many vulnerable older people in the UK living in poverty - unable to afford decent food, heat their home or live an independent life - when billions of pounds in benefits are unclaimed," said Caroline Abrahams, charity director at Age UK.
Meanwhile, the government says it is trying to help more pensioners understand what benefits they are entitled to and how to claim for it.
"We are absolutely determined to make sure that pensioners receive the full support they are entitled to - with as little hassle as possible," said a spokesman for the Department for Work and Pensions (DWP).
The DWP said that people can claim housing benefit and pension credit in just one free phone call on 0800 99 1234, without the need for a signed form.
What Benefits Pensioners Are Entitled To
Pension credit: 1.6 million pensioners are missing out on average £33 a week
Council tax benefit: 2.2 million pensioners are missing out on average £728 a year
Housing benefit: 390,000 pensioners are missing out on average £48 a week