an extraordinary alliance of countryside campaigners, wildlife groups and green activists today launches a savage onslaught on the government over its "stunning disregard" for the environment.  The attack - backed by organisations including the RSPB and the Campaign to Protect Rural England - is a significant embarrassment for David Cameron who claimed at the last election that his would be the "greenest government ever".  However, in letters to the Observer, green groups - including the umbrella organisation the Wildlife Trusts, which has more than 800,000 members - ridicule this claim and vent their fury over last week's autumn statement by George Osborne. With the government outlining cuts in solar energy subsidies, reforming planning regulations and introducing tax support for energy-intensive industries, the chancellor infuriated the green lobby with the tone of his comments. "Far from being the greenest government ever, this government is set to seize the mantle of most environmentally destructive in recent history," states one letter, signed by the green campaigners Tony Juniper, Jonathon Porritt, Caroline Lucas, who is the leader of the Green Party, and others.  a second letter, from the heads of the RSPB, Greenpeace and others, says: "Rarely have we been as incredulous as we were on Tuesday, upon hearing the autumn budget statement.  "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 on green issues.  In terms that many MPs saw as at odds with the government's professed enthusiasm for the environment, Osborne told the Commons on 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." Several leading Liberal Democrats are known to be furious, and fear that the government is back-tracking on its commitments. One senior minister said that he failed to understand why Osborne had chosen to question the green agenda, both in the autumn statement and his party conference speech in October. The minister said: "If George goes down this route, he fires an Exocet missile right through David Cameron's political integrity."  Ministers insist that, despite some hostile rhetoric on green issues, the government is still pursuing a radical agenda including subsidies for other areas of renewable energy, and the signing earlier this year of the fourth carbon budget that commits the UK to bold cuts. 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 rhetoric could put on the econ