The number of UK households in fuel poverty has dropped from 5.5 million in 2009 to 4.75 million in 2010.
The fall was mainly due to rising incomes, relatively stable energy prices at the time and reduced energy consumption, according to the 2012 Annual Report on Fuel Poverty released by the Department of Energy and Climate Change (DECC).
Northern Ireland remains the most fuel poor part of the UK, with estimates suggesting 44% of households spend more than 10% of incomes on energy bills. In Scotland, 28% of the population are fuel poor, Wales is at 26% but England drops to 16%.
The rise in energy prices last year is expected to increase the number of households in fuel poverty again, although the figures will not be published until 2013 and 2014, DECC said.
Projections for England indicated there were likely to be around 3.5 million fuel-poor households in 2011 and 3.9 million in 2012.
Energy and climate change minister Greg Barker said: "I am encouraged by the fall in fuel poverty in the period to April 2011, but there is no room for complacency. Fuel poverty remains a serious national problem and the coalition is absolutely committed to tackling it."
Consumer groups warned that recent price increases meant the figures were likely to underestimate the current problem. Consumer Focus director of energy Audrey Gallacher said: "Today's figures show a dip in fuel poverty levels in 2010 reflecting lower energy prices.
"But as the average annual bill has risen by over £150 since then, many more people are now affected. Millions of families, older people and disabled people, living on low incomes, will be facing tough daily decisions on what essentials they cut back on to make ends meet.
"Current Government plans are not sufficient to tackle the scale of this problem. This is clearly demonstrated by the more than 50% cut in energy efficiency help for the homes of the poorest households in England when fuel poverty levels are on the rise."
National Energy Action (NEA) chief executive Jenny Saunders said: "Since this statistical analysis was undertaken we have entered a period of profound economic austerity accompanied by continuing increases in domestic gas and electricity prices. NEA estimates that additional gas and electricity price increases in 2011 mean that more than five million households in England now face unaffordable energy costs."