The Government's poor record on the environment in the UK will undermine its efforts to play a leading role at a key global summit on the issue, campaigners claim.
Friends of the Earth accused the coalition of supporting fossil fuel companies while failing to back renewables or protect nature and the countryside, putting "economic growth at all costs" above sustainable development.
The green group criticised the Prime Minister for failing to attend the Rio+20 summit, marking 20 years since the original Earth Summit held in Rio de Janeiro, Brazil, which will focus on sustainable development.
It called on Deputy Prime Minister Nick Clegg, who is attending the summit next week, to ensure it does not not undermine existing agreements on sustainable development and is not hijacked by those who want to maintain "business as usual".
Friends of the Earth also called for the Government to take action at home, including by helping households struggling with high energy bills by developing clean energy sources in the UK and cutting energy waste.
Action is also needed to save British bees, protect nature, reduce consumption and put sustainable development at the heart of all polices from town planning to farming and the food system.
The call comes after a series of sombre warnings from the United Nations Environment Programme and scientists that the world was on track to hit "tipping points" that would cause major changes to the planet, seriously damage the natural resources humans depend on to survive.
Expectations that Rio+20 will take major steps forward to tackle environmental problems have been played down, but it is expected to launch a process to agree new global goals for sustainable development.
Environment Secretary Caroline Spelman told MPs that the Prime Minister's decision not to attend the conference did not mean that the UK was not taking it seriously.
Speaking to the Environmental Audit Committee before travelling to Rio de Janeiro, Mrs Spelman said David Cameron was attending the G20 meeting in Mexico and did not want to be out of the country too long amid the Eurozone crisis.