With the government outlining cuts in solar energy subsidies, reforming planning regulations and introducing tax support for energy-intensive industries, the chancellor's rhetoric has infuriated the green lobby. "Following the chancellor's autumn statement, we can say that the coalition is on a path to becoming the most environmentally destructive government to hold power in this country since the modern environmental movement was born," states one letter, signed by the green campaigners George Monbiot, Tony Juniper, Jonathon Porritt, Caroline Lucas, leader of the Green Party, and others.
A second letter, from the heads of the RSPB, Greenpeace and others, says: "The stunning disregard shown for the value of the natural environment not only flies in the face of popular opinion but goes against everything the government said in June, when it launched two major pieces of environmental policy – the natural environment white paper and the England biodiversity strategy."
The backlash comes as serious tensions are developing inside the Tory/Liberal Democrat coalition over green policy. The Observer understands that the Liberal Democrat energy secretary, Chris Huhne, was not consulted by Osborne about his comments in the autumn statement. In terms that many MPs saw as at odds with the government's professed enthusiasm for the environment, Osborne told the Commons last Tuesday: "We are not going to save the planet by shutting down our steel mills, aluminium smelters and paper manufacturers. All we will be doing is exporting valuable jobs out of Britain."
Osborne also said he wanted to ensure that "gold plating of EU rules on things like habitats" was not putting "ridiculous costs" on firms. Several leading Liberal Democrats are furious, and fear that the government is backtracking on its commitments. One minister said he could not understand Osborne's behaviour. The minister said: "If George goes down this route, he fires an Exocet missile right through David Cameron's political integrity."
Tim Yeo, the Tory chairman of the energy and climate committee, said: "We are getting a change of rhetoric, with more emphasis on the burdens that green projects could put on the economy. But it is out of step with what the government is doing, much of which is radical and forward-looking."
Labour claimed on Saturday that the Tories were undergoing a "retoxification" as they abandon the softer image they promoted before the last general election.
The dispute intensified as delegates gathered for the latest climate change summit in Durban. The meeting's goal of further progress on global emissions is unlikely to be met as developed nations continue to fret over their own domestic financial woes.
Earlier this year the government infuriated many traditional Conservative party supporters when it emerged that it was planning to sell many of the nation's forests. Following an outcry from countryside and environmental groups the policy was abandoned. Since then it has been locked in an equally damaging row over plans to loosen planning controls that many Tories feel would threaten the countryside.
Now environmentalists fear more damage from large-scale developments – including port and road schemes. They cite the north Norfolk coast, the North Yorkshire moors, the Wye valley and the Salisbury plain as large areas of natural and untouched beauty that could be under threat.
Many Tories are also concerned about potential environmental damage from the proposed HS2 highspeed rail line between London and Birmingham.
The transport secretary, Justine Greening, is expected to announce a delay in the final decision on the project this week in order to examine whether funding estimated at £500m could be used to pay for a new tunnel under the Chiltern hills.
A treasury spokesman said: "This is the government that introduced the first green investment banks, the carbon price floor and the green deal. Our planning reforms strike the right balance between protecting our countryside [and] permitting economic development that creates jobs."