The government has been accused of "shifting the goalposts" to bring down the number of households classed as in fuel poverty.

Amendments to the Energy Bill would change definitions so that 2.4 million people were classed as fuel poor rather than 3.2 million.

A report from the Commons environmental audit committee pointed out that currently families fall into the category if they spend more than 10% of income on fuel "to maintain an adequate level of warmth".

But the new indicator would mean they were regarded as in hardship only if they have "above average fuel costs" that would leave them with "a residual income below the official poverty line".

The Labour MP Joan Walley, who chairs the cross-party committee, said: "The government is shifting the goalposts on fuel poverty so that official statistics record far fewer households as fuel-poor.

"The changes to the fuel poverty definition and target, in part being made through amendments to the Energy Bill, should be stopped unless the government is prepared to make a public commitment to end fuel poverty altogether."

A spokesman for the Department of Energy and Climate Change said:

"The changes to the fuel poverty definition helps to get a better understanding of the causes and depth of fuel poverty, and to target policies more effectively.

"There is already a range of help for those in most need, including the warm home discount, winter fuel payments and cold weather payments."

Walley also warned that the coalition's shake-up of green levies – intended to shave £50 off average annual bills – could end up hitting fuel-poor households.

"A short-term bid to cut bills must not throw energy and climate change policy off-course," she said.

"In the longer term green levies could actually keep bills down if they drive energy efficiency improvements that cut the cost of heating our homes.

"Insulating homes and supporting green technologies is vital to help the fuel poor and cut the emissions causing climate change."