The need for action to avert a looming climate catastrophe was rammed home by graphic images of melting glaciers and makeshift sea defences displayed at the venue of the meeting.

"We must make climate stability, energy investment and energy security central to economic policies," British Chancellor of the Exchequer Gordon Brown told the meeting. "International cooperation is again the only way forward."

Brown said he would study the costs and feasibility of so-called carbon sequestration -- the capture and burial deep underground of millions of tonnes of the carbon dioxide emitted by fossil fuel burning power stations.

The Kyoto Protocol on cutting emissions of greenhouse gases came into force in February but is still shunned by the world's biggest emitter, the United States, and puts scant limits on China as it rises fast up the pollution ranks.

Senior officials from both countries attended the London meeting, aiming to discuss ways to achieve the environmental Holy Grail of sustainably growing low carbon economies.

The U.S delegate made it clear energy efficiency, not a radical shift to a low carbon economy, should be the key.

"We are now trying to find a portfolio in which three words are important, technology, technology, technology," US President George W. Bush's chief environment adviser James L. Connaughton said before the meeting.

"RICH NATION HYPOCRISY"

As about 30 people banged pots and pans in the street outside to protest at what they said was rich nation hypocrisy, speakers stressed the need to cut greenhouse gas emissions, improve energy efficiency and switch to renewable resources.

And that did not just mean wind and wave power. Nuclear power -- anathema to the green lobby -- had to remain an option.

"We will keep the nuclear option open," British Trade and Industry Secretary Patricia Hewitt said, noting that while it was a low carbon technology there were major questions over its true costs and the problem of nuclear waste storage.

Liu Jiang, leading the Chinese delegation, went even further stressing that nuclear power was clean and saying that China was embarking on a major investment programme in nuclear reactors to reduce its massive dependence on burning coal.

He also urged the rich, developed world which owns most of the cutting edge green technology to make it more readily and cheaply available to developing countries as they try to climb the steep slope out of poverty.

Jacques Dubois, chairman of the giant SwissRe reinsurance company that underwrites insurers' risks, said his experts considered the risks to people and property from climate change to be a major problem for the future.

The London meeting is part of Britain's agenda for the G8, which Prime Minister Tony Blair has vowed will make progress on climate change and African development.