Around six million households plan to cut back on heating this winter as millions of pounds of Government help for those on low incomes goes unclaimed, consumer groups have said.
Nearly four out of 10 households (39%) are worried about affording their energy bills this winter, and 70% of those, or six million households across England, plan to cut back on heating, found a survey for the Consumer Focus watchdog.
But millions of pounds available through the Government's Warm Front scheme to help the poorest households with insulation and cutting bills is being left unclaimed, Consumer Focus, Citizens Advice, Age UK and the National Children's Bureau said.
The organisations are jointly urging those worried about their bills to find out if they are eligible for the scheme, which the Government has revealed was underspent by more than £50 million over the last year.
Consumer Focus programme director Jonathan Stearn said: "A cold home can damage your health, so it's very worrying that high energy prices are leading so many people to cut back on their heating.
"We want to make sure that as many people as possible are helped to cut their bills and stay warm and well through the Warm Front scheme this year. We would urge anyone struggling with their bills to find out if they can claim free help."
Age UK spokesman Mervyn Kohler said: "Warm Front is being phased out. When this year's budget is exhausted, that's it. But so far applications are really low and the scheme may gift an underspend back to the Treasury. A cold home is a serious health hazard, and older households, who are particularly at risk, can act now, knowing that by Christmas they will be warmer and better prepared for the dangers and worries of a cold winter."
Rachel Monaghan, senior development officer of health and wellbeing at the National Children's Bureau, said: "Some families with children in the UK will have to make the choice whether to heat or eat this winter.
"We know many families are struggling to cope with rising fuel bills and are having to cut back on other essentials like food. We also know that growing up in a cold and damp home can have a real effect on children's health, learning and enjoyment of life. The Warm Front scheme can help cut bills and keep families warm and healthy, so we urge anyone worried about their fuel bills to find out as soon as they can if they are eligible to receive support."
Citizens Advice said it could help with applications for a Warm Front grant.