Gordon Brown’s target to pull vulnerable families out of fuel poverty by 2010 was all but abandoned on Thursday after figures showed a sharp rise in people struggling to pay energy bills.

About 3.5m households were found to be “fuel poor” in 2006, according to government figures – an almost 40 per cent increase on 2005.

Fuel poverty levels are now at their highest since Lab­our came to power. Unions and campaigners expect the figure to increase significantly this winter as energy prices rise further.

Whitehall officials say that with about 2.75m “vulnerable” households – containing a child, someone chronically ill or an elderly person – falling under the poverty line, it will be “very, very difficult” to meet the goal of eliminating fuel poverty for the vulnerable. Ministers have also pledged to eradicate all fuel poverty by 2016.

Hilary Benn, the environment secretary, insisted the government was still committed to tackling fuel poverty but admitted that “sharply rising energy price rises have made this goal increasingly difficult”.

Unions responded by reiterating calls for a windfall tax and poured scorn on government energy efficiency measures. Tony Woodley, joint general secretary of Unite, said: “It is time to stop talking to these companies about lagging the lofts and start making them do their duty by those in desperate need.”

The call to punish energy groups was dismissed by Phil Wollas, the environment minister, who said there was “no guarantee that a windfall tax would not be passed on to the customer. We can only regulate in the UK; we can’t regulate Saudi Arabia.”

Ministers will face further embarrassment on Monday as campaigners Help the Aged and Friends of the Earth go to the High Court seeking a judicial review of the government’s fuel poverty pledges, claiming that there are no concrete plans in place to meet them.

Mervyn Kohler, of Help the Aged, said: “Low-income households need crisis payments simply to get through the coming winter but, in the longer term, the energy efficiency of our homes must be improved.”

Fuel poverty is defined as households who spend more than 10 per cent of their income on fuel bills. Ministers said the rise in their number was primarily the result of the 22 per cent increase in consumer energy bills between 2005 and 2006.

Copyright The Financial Times Limited 2018. All rights reserved.

Comments have not been enabled for this article.