A Centrica report on rising domestic gas bills has triggered a torrent of abuse from the Conservatives and the Liberal Democrats, who are calling on the government to do more to help poorer households before the winter.
"Frankly it's frightening that the Government has no strategy for protecting the poor against rising prices," said shadow energy minister Charles Hendry.
"These price hikes will push well over a million more people into fuel poverty and pile on the pain to consumers already being hit by prices at the pumps and the checkouts," he continued.
"The government needs to act immediately before this winter turns from a concern into a crisis."
The Liberal Democrats said energy companies had recently received a £9 billion windfall due to the European emissions trading scheme and that they should use the money for a "massive home energy efficiency programme".
Commenting on warnings home energy bills could rise by 60 per cent, party leader Nick Clegg said: "The time has come for the government to admit that many families are going to face an increasingly difficult struggle paying their fuel bills.
"As the winter approaches, the energy firms should also be making sure that the poorest and most vulnerable customers are offered the best deals."
The government has promised £225 million from energy companies to go towards their poorer customers, but analysts say that figure will only help 100,000 people, when over five million need assistance.
Karen Jopley, head of public affairs at Friends of the Earth said the initiative "will only just begin to scratch the surface".