The charge led by French President Jacques Chirac came a day after the release of a scientific report in Paris that said global warming is “very likely” caused by mankind and that climate change will continue for centuries even if heat-trapping gases are reduced. It was the strongest language ever used by the Intergovernmental Panel on Climate Change, whose last report was issued in 2001.

The document, a collaboration of hundreds of scientists and government officials, was approved by 113 nations, including the US.

Despite the report’s dire outlook, most scientists say the worst disasters — huge sea-level rises and catastrophic storms and droughts — may be avoided if strong action is taken soon.

In his call to action at a French-sponsored environment conference on Saturday, Mr Chirac said: “It is our responsibility. The future of humanity demands it.”

Without naming the US — producer of about 25% of the world’s greenhouse gases — he expressed frustration that some large, rich countries are “refusing to accept the consequences of their acts.” So far, it is mostly European nations that agreed to pursue plans for the new organisation, and to hold their first meeting in Morocco this spring.

Mr Chirac, 74, is seeking to leave his mark on international affairs before he leaves office, though his own environmental record over 12 years as France’s president is spotty.

Former US Vice-President Al Gore, whose Oscar-nominated documentary on global warming won worldwide attention, cheered Mt Chirac’s efforts.

“We are at a tipping point,” Gore told the conference by videophone. “We must act, and act swiftly. Such action requires international co-operation.”

Other international leaders said that the science is so well-documented, action is clearly the next step.

However, many questions remain about Mr Chirac’s proposed new body, including whether it would have the power to enforce global climate accords. Mr Chirac’s appeal says only that the group should “evaluate ecological damage” and “support the implementation of environmental decisions”.

Many countries have failed to meet targets for cutting greenhouse gas emissions laid out in the 1997 Kyoto Protocol. The US has never ratified the pact and on Friday it reiterated its rejection of imposed cuts on greenhouse gases.

Earlier this week, Mr Chirac warned the US could face a carbon tax on its exports if it does not sign global climate accords.

The EU has committed to a 20% drop in carbon pollution by 2020.