Rising gas and electricity prices pushed another million households across the UK into fuel poverty, figures from the Department of Energy and Climate Change (Decc) show today.
The number of households suffering from fuel poverty judged as spending more than 10% of income on keeping homes warm reached 5.5 million in 2009, the latest year for which figures are available.
Lobby groups estimate the figure is likely to soar when prices hikes in August come into effect.
Decc says the latest rise in fuel poverty levels, which have been increasing since 2004, was largely due to rising fuel prices which saw gas costs jump by 14% and electricity by 5% that year.
The majority of fuel poor households across the UK were considered to be vulnerable - those with elderly, disabled or long-term sick people or children.
There were 4.5 million UK households classed as vulnerable who spent more than a 10th of their income on heating their homes in 2009, a rise of 750,000 from 2008 figures. A vulnerable household is one that contains the elderly, children or somebody who is disabled or long term sick.
Mark Todd, director of price comparison site Energyhelpline.com, says: "These figures represent an absolute tragedy for such a supposedly advanced nation as the UK."
The latest data on the struggle people are facing over fuel bills comes just days after British Gas announced another price hike, citing rises in wholesale gas costs, which will see gas and electricity bills jump by 18% and 16%, respectively, on average.
Last month, Scottish Power announced a similar hike in bills and the rest of the "big six" suppliers are expected to follow in the coming weeks.
Lobby group Consumer Focus says as many as 6.4 million households could be in fuel poverty following the rises expected in the coming months.
Audrey Gallacher, director of energy at Consumer Focus, says: "Fuel poverty levels are set to soar as energy price hikes and the cost of investment in making our energy supply more secure and sustainable kick in.
"Increasing energy costs create hardship for millions of the poorest pensioners, families and disabled people, leaving many cutting back on heating or other essentials. It is an issue which cannot be left on the backburner."
However, Decc says figures for the levels of fuel poverty for 2010 and 2011 would only be known in the next couple of years, and the effect of the latest rises in household energy bills would not be fully felt until 2012.
The department estimates that in 2010, there were still 4 million homes in England in fuel poverty, a figure which was expected to rise slightly to 4.1 million homes in 2011.
Officials say rising incomes, improvements in energy efficiency of housing and social and discounted tariffs had prevented some people from falling into fuel poverty, and had even lifted some homes out of the situation.
But Climate Change minister Greg Barker says: "I know rising energy prices are hitting households hard. These new figures show the old policies to help the most vulnerable were not working.
"That's why, this year, we've introduced the Warm Home Discount which will require the Big Six energy companies to provide discounts of at least £120 to about 600,000 of the poorest pensioners.
"We're also pushing for stronger competition to keep price rises as low as possible.
"In the longer term, we'll be helping people use less energy with the Green Deal which will provide extra support for the poorest and most vulnerable to benefit from energy efficiency measures."
The Green Deal is the Government's flagship energy efficiency programme, which aims to cover the upfront costs of work on homes to make them more efficient, for example, by installing new boilers, insulation and small scale renewables.