The prime minister must pledge to attend next year's Rio+20 summit to show leadership in tackling the global environmental crisis, according to a group of MPs.
The House of Commons environmental audit committee suggests that the move would reinforce the UK's commitment to a low carbon economy and help boost the profile of the conference.
The summit, to be held in Brazil next June, is set to focus on the "green economy" and sustainable development, but there are no binding agreements or treaties currently on the table for the conference.
However, David Cameron will be unable to attend as the June date as it coincides with the Queen’s Diamond Jubilee celebrations.
Instead, government sources have confirmed that that environment secretary Caroline Spelman will lead the UK delegation.
The cross-party group of MPs had warned that Earth's environmental problems are now much more urgent than the Rio summit held in 1992.
The committee said safe limits on the amount of waste, pollution and biodiversity loss that natural systems can tolerate continue to be breached, undermining the ability to use natural resources to support further growth.
It found there had not been enough progress on sustainable development since the 1992 summit in Rio de Janeiro and said increasing pressure on natural resources had made the need for action even more urgent.
The Millennium Development Goals, which aim to improve the lives of the world's poorest people, were unlikely to be met by their 2015 end-date, the MPs said.
The report recommended the UK works towards launching new goals for sustainable development and sustainable consumption by rich countries.
It also said the government should appoint a "special envoy" to promote the Rio summit to the wider public and co-ordinate government departments to ensure they all play thier part.
Committee chair Joan Walley said: "The Rio+20 Earth Summit is a vital chance for world leaders to take action to avert a global environmental crisis.
"But the financial situation means minds will be focused elsewhere and there is a danger that business-as-usual may end up carrying the day.
"The prime minister should lead by example. He could make a big difference by demonstrating his commitment to Rio + 20 and letting other world leaders know that he will personally be attending.
"Lasting prosperity can only be built on a healthy planet."

Dods Parliamentary Communications Ltd
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