There has been a surge in the number of people seeking help from Citizens Advice Bureau (CAB) offices about their growing fuel bills.
Up to 4.6 million households in England could be in fuel poverty in 2009, according to a government report.
The CAB for England and Wales says the number of people coming through its doors between April and September was 46% up on the same period last year.
There were four million fuel-poor households in the UK in 2007, up from 3.5 million in 2006, Department of Energy and Climate Change figures show.
The latest official figures on fuel poverty will be published by the government later.
Fuel poverty is defined as those who spend more than 10% of their household income on heating their homes.
The CAB said most people it was seeing were poor but in work.
The government has vowed to eradicate fuel poverty in all households in England by 2016.
"We are already seeing large increases in the number of people in fuel debt and it is not yet winter," said David Harker, the chief executive of Citizens Advice.
"Recent government increases in Warm Front Grants and Cold Weather Payments will go someway towards helping but information on what help is available, targeted to those who are most vulnerable, must be a prime focus for the government and energy companies," he added.
Wholesale prices
Average fuel bills are now at record levels, mainly because of the surge in wholesale gas prices in the past few years.
This has been driving up the number of people in fuel poverty - defined as those who spend more than 10% of their income on heating their homes.
A typical household now pays more than £1,000 in combined gas and electricity charges a year and Ofgem warned this month that energy bills might rose by a further 60% between now and 2016.
The regulator said that the average annual household gas bill went up by 120% from September 2000 (£365) to September 2009 (£804).
At the same time the average annual household electricity bill rose up by 48% from £299 to £443.
A year ago the number of households in fuel poverty in England had risen to four million, up sharply from just 1.2 million in 2004.
Of those about half were pensioners, according to figures from the Fuel Poverty Action Group, a government sponsored advisory committee.