Disabled people struggling to pay fuel bills could doubleCharities estimate that the number of people with disabilities who are severely struggling to pay energy bills could more than double this year.
At present, about 900,000 people with disabilities are considered to be in fuel poverty, according to Scope and National Energy Action.
If typical domestic bills rise to £3,000 in October, as feared, they said that number could rise to 2.1 million.
The government has said it is supporting people facing rising costs.
Chancellor Rishi Sunak, who delivers his Spring Statement on Wednesday, has pledged to help "where we can make a difference".
The charities said that people with disabilities often had additional energy needs compared to people without disabilities, as many needed to keep heating on for medical reasons, or use electricity to power vital equipment.
"Disabled people are already facing some extremely difficult choices, and this is only going to get worse in the months ahead unless action is taken now," said Mark Hodgkinson, chief executive of Scope, a disability equality charity.
Millions of households are facing a 54% rise in the cost of a typical annual gas and electricity bill, to about £2,000, when the regulator's new, higher price cap takes effect on 1 April.
The war in Ukraine has pushed up wholesale energy costs, leading to worries that the typical household bill could rise to as high as £3,000 in October, when the cap will be adjusted again.
The government has said it is taking "decisive action" in helping people with their bills. This includes a £150 council tax rebate for 80% of households, followed by a £200 discount on bills in October which will need to be repaid.
National Energy Action, which campaigns for warm and dry homes, has called on the chancellor to allow low-income and vulnerable people an exemption from repaying the £200 grant.
Adam Scorer, the charity's chief executive, said: "As heat prices spiral, it is the most vulnerable who suffer the most. A warm, safe home is an absolute necessity for people with disabilities. The impact of a cold home on their mental and their physical health can be catastrophic.
"The current level of support is woefully inadequate. Government must provide greater financial support, or some of the most vulnerable in society will count the cost in more than just pounds and pence."