They said major divisions had emerged at the G8 summit between the world's richest nations on how to tackle climate change.
The US wants to trade internationally-agreed pollution permits with Russia while pressing developing countries to agree legal commitments to reduce climate-changing pollution. It is understood that both plans are being resisted by European countries.
Tony Juniper of Friends of the Earth said: "If the G8 supports such pollution trading, international efforts to prevent catastrophic climate change could be fatally damaged."Reuse content