Pensions minister Steve Webb has revealed that over one million pensioners could be entitled to extra cash via the current Pension Credit system.
According to Mr Webb, a total of £2.93 billion worth of Pension Credit remains unclaimed each year, with around 1.6 million people that are eligible for the money failing to claim.
The Department of Work and Pensions estimated that people could be missing out on around £3,000 a year at a weekly Pension Credit award average of £57 a week.
Some of these low income pensions could also be entitled to Cold Weather Payment too, with those signing up for Pension Credit also eligible for money if the average temperature over seven consecutive days is recorded or forecast to be zero degrees Celsius or below.
The MP said: "I am very concerned that over a million pensioners could be missing out on Pension Credit cash of up to £137.35 a week.
"If anyone thinks a family member, a friend or neighbour might be entitled to Pension Credit, I'd encourage them to ask them to get in touch and find out."
All Pension Credit and Cold Weather Payments can be backdated by up to three months with those entitled to the payments invited to call 0800 99 1234 for more help.