A Liberal Democrat Cabinet minister today accused right-wing Conservatives pressing for the scrapping of environmental taxes on energy bills of being "full of crap".
Danny Alexander, Chief Secretary to the Treasury, stoked up Coalition tensions as he responded to newspaper claims that David Cameron had instructed aides to "get rid of all this green crap" pushing up gas and electricity prices.
Although Downing Street insisted it did not recognise the phrase, the reports triggered anger among senior Liberal Democrats and green groups, as well as an extraordinary attack by a prominent Conservative MP on the Prime Minister.
Mr Alexander said green levies on energy were designed to help insulate the homes of poorer families and create tens of thousands of jobs by investing in future energy sources.
In a swipe at his Tory Coalition colleagues, he said: "Anyone who thinks we should get rid of that is full of crap."
Nick Clegg also insisted such levies are not "all crap" and made clear the Government would not retreat from its environmental agenda.
The row broke out after a senior Tory source was quoted describing how the Prime Minister is "going round Number 10 saying 'we have got to get rid of all this green crap'".
The source added: "We used to say 'vote blue, go green', now it's 'vote blue, get real'."
The reported comments represented a stark contrast with Mr Cameron's promise to head the "greenest government ever" and his famous trip to the Arctic after becoming Tory leader to witness the impact of climate change.
Downing Street's efforts to play down the report failed to placate the Tory MP Zac Goldsmith, a long-standing environmental campaigner, who attacked the apparent change of heart.
He tweeted: "'If the PM can casually drop something that was so central to his identity, he can drop anything' - tea room Tory chat."
Tim Yeo, the Tory chairman of the Commons energy select committee, said he did not believe Mr Cameron would have used the phrase, blaming the report on a "bit of mischief".
But he acknowledged: "There are elements within the Conservative Party which would like the Prime Minister to drop these energy measures."
Craig Bennett, the policy and campaigns director for Friends of the Earth, said: "It would come as little surprise if David Cameron did tell aides to ditch the 'green crap' - his Government has been attacking environmental policies for years.
"If the Prime Minister wants to stop the drift back towards the toxic Tory party of the past he must take urgent and decisive action to rebuild his eco-credentials."
Joss Garman, Greenpeace's deputy political director, said: "If David Cameron thinks the road to electoral victory will be found in attacking the very policies he once passionately advocated then he is sorely mistaken.
"The British electorate are a sophisticated bunch who will see through his chameleon tendencies and conclude this attack is not an act of leadership, but one of cowardice as he panders to the extreme wing of his own party and tries to claw back support from Ukip."
Meeting supporters of the HS2 rail project outside Downing Street yesterday, Mr Cameron stressed his continued support for the environmental agenda.
He said: "This is a part of it. We have got the world's first green investment bank, we have got great support for our green technology industries. We have got the first nuclear power station since 1995. This is a Government investing in important green technologies."
Downing Street also insisted Mr Cameron remained as committed as ever to the green agenda.
However, green groups have warned that the environment is slipping down the Government's priorities. The Independent reported last year that Chancellor George Osborne had started using the phrase "environmental Taliban" to poke fun at the green lobby within the Coalition and the Conservative Party.
Mr Cameron told the Commons last month he wanted to "roll back" the green levies which add an average £112 a year to energy bills to fund renewable power subsidies and programmes to insulate homes. An announcement is due on December 5 in Mr Osborne's autumn statement.
Mr Clegg confirmed yesterday that the Warm Homes Discount, which gives a £135 rebate to 2m poorer households, could be switched from fuel bills to general taxes.
But he stressed: "We are not going to abandon the long-term objective of making sure we reinvest in our energy infrastructure to keep the lights on."