Over half of all children in poverty are missing out on support to keep their homes warm, according to a new report.
The Children's Society claims nearly two million poor children are in families that are not getting the Warm Home Discount, which provides a £135 rebate on fuel bills.
Most of them miss out because the support available for low income families is limited, while others do not know the scheme exists, the charity found.
An estimated 400,000 poor children in London are missing out.
The Children's Society's chief executive Matthew Reed said: "It is alarming that huge numbers of children across the UK are growing up in a cold home. The scale of the problem, as these figures show, is truly appalling.
"The Government must take decisive action now to move children in from the cold and help stop their parents from having to make this terrible choice between heating and eating.
"By making the Warm Home Discount automatically available to all children living in poverty, the Government can give these families a lifeline to help them out of poverty, and they should do it now."