The first formal talks in the long process of drawing up a replacement for the Kyoto climate change pact opened in Thailand on Monday with appeals to a common human purpose to defeat global warming.

"The world is waiting for a solution that is long term and economically viable," U.N. Secretary-General Ban Ki Moon said in a video address to the 1,100 delegates from 163 nations gathered in Bangkok.

The week-long meeting stems from a breakthrough agreement in Bali last year to start negotiations to replace Kyoto, which only binds 37 rich nations to cut emissions of greenhouse gases by an average of five percent from 1990 levels by 2012.

U.N. climate experts want the new pact to impose curbs on all countries, although there is wide disagreement about how to share the burden between rich nations, led by the United States, and developing countries such as China and India.

It will also be crucial to work out how big industries, such as power generators, airlines and steelmakers will play their part in tackling rising emissions of greenhouse gases, such as carbon dioxide.

The United Nations climate panel says it is crucial for greenhouse gas emissions to peak in the next 10-15 years and then fall sharply if the world is to avoid the worst effects of global warming.

No major decisions are likely from the Bangkok talks, which are intended mainly to establish a timetable for more talks culminating in a United Nations Climate Change conference in Copenhagen at the end of next year. Delegates said Monday's talks would be merely procedural.

"We see this as very much a process-oriented meeting," chief U.S. climate negotiator Harlan Watson told reporters before the opening ceremony.

COMMITMENT

However, environmental groups are keeping a close eye on Bangkok for signs of sustained commitment by rich and poor countries alike to minimising global warming by curbing emissions.

"It's the first test of whether the goodwill and good intentions that were present in Bali are still there when they get down to the hard negotiations," said Angela Anderson of the Washington-based Pew Environment Group.

U.N. climate change chief Yvo de Boer said the replacement for Kyoto would be the "most complex international agreement that history has ever seen", suggesting talks would be tough and tortuous but possible if the work was tackled in "bite-sized chunks".

Spurring on negotiators will be last year's landmark acceptance at U.N. climate panel talks that humans are almost certainly to blame for changes to the weather system that will bring higher sea levels and more heatwaves, droughts and storms.

One major issue to be tackled is the reluctance of big developing nations such as India and China to agree to any measures that might curb their rapid industrialisation.

Negotiators will also have to work out how to deal with the United States -- the only rich nation not to have signed up to Kyoto -- given that President George W. Bush will be leaving the White House after November's election.

"The USA needs to ratify Kyoto. If they do not, they should not be allowed a voice in the discussions on future commitments under the Kyoto Protocol," Greenpeace said in a statement.

Bush pulled the United States out of Kyoto in 2001, saying the pact would hurt the economy and was unfair since it excluded big developing nations from committing to emissions cuts.

The White House has since moderated its stance by saying it would accept emissions targets if all other big emitters do as well based on their individual circumstances.

The United Nations wants the new treaty to be in place by the end of 2009 to give companies and investors as much advance knowledge as possible of coming changes, and national parliaments time to ratify it before 2012, when Kyoto expires.