Age Concern yesterday launched Your Rights Week, which is designed to improve benefits take-up among pensioners. The charity said millions who failed to claim a range of State benefits were collectively missing out on £2.9bn a year.
Gordon Lishman, Age Concern's director-general, said: "Year after year, we hear of the most distressing cases of poverty - the system can seem daunting but it is definitely worth making a claim."
Benefits on which pensioners regularly miss out include the Pension Credit, Council Tax Benefit, Housing Benefit and Attendance Allowance.
Of the 4.8 million pensioners eligible to claim the Pension Credit, which is paid as a top-up to other State pensions, just 3.2 million are receiving it. Similarly, 1.8 million pensioners are missing out on Council Tax Benefit, worth £870m a year.
The initiative follows the publication this week of the latest Department of Work and Pensions (DWP) figures on pensioner incomes. The DWP said the average pensioner couple now had to get by on £345 a week after tax, a 17 per cent increase on 1997 after taking into account the effects of inflation.
The average single pensioner has £181 to live on according to the DWP, a 22 per cent real increase on 1997.
However, the rise in incomes has partly been achieved through a greater number of means-tested benefits for those in most need of extra money. Critics of the strategy point out that pensioners often have to complete complicated forms to qualify for the cash, which deters many from claiming.
Mervyn Kohler, head of public affairs at Help the Aged, said: "It is unacceptable to have so many pensioners missing out on the benefits they are entitled to - this is a ridiculously muddled way to deliver support to older people."
Age Concern is running a free telephone helpline with benefits advice. Call 0800 006699.