Negotiations seeking a global pact to tackle global warming are troubled and could end in disastrous failure, China's top climate change envoy warned on Monday, saying rich countries are failing to deliver on promises.

China is emerging as the world's top emitter of the greenhouse gases that stoke dangerous global warming and plays a key role in talks to address the threat. These are supposed to culminate in a new deal in Copenhagen, Denmark, late next year.

But Yu Qingtai, China's special representative for climate change talks, told Reuters he was gloomy about the discussions to create a treaty building on commitments laid out in the Kyoto Protocol's first phase, which expires at the end of 2012.

'As far as the Copenhagen process is concerned, my personal assessment is unfortunately fairly pessimistic...things have moved forward in an extremely difficult way and the progress achieved is extremely limited,' Yu said in an interview.

In preliminary talks, rich nations had failed to flesh out their promises to give technology and financing help to poorer countries, he said.

The global financial turmoil draining government budgets should not be 'used as an excuse by the developed country governments for not meeting their commitments,' he added.

China's rising greenhouse gas emissions, which experts believe have already or will soon surpass those of the United States, have prompted many Western politicians and experts to argue that Beijing must accept mandatory caps if the United States and other reluctant countries are to agree to emissions cuts.

Under current agreements, China and other developing countries need not take on greenhouse gas caps under Kyoto.

Yu rejected calls for this to change, instead blaming foot-dragging by richer nations and leaving little doubt that talks leading to Copenhagen will be combative.

But failure to reach agreement by late next year could exact a terrible price, he said. Scientists have warned that growing levels of solar heat held in the atmosphere by a blanket of carbon dioxide and other pollutants are stoking droughts, melting glaciers and intensifying wild weather.

'I would not even try to contemplate,' he said. 'If we fail, the consequences would be disastrous for everybody.'

German Foreign Minister Frank-Walter Steinmeier said last week the market difficulties would make it harder to agree a climate deal, while US Democratic presidential candidate Barack Obama has said he might be forced to scale back his planned investments in energy.

Cross-Border Emissions

Spelling out China's demands, Yu said any final deal must reflect rich countries' responsibility for gases emitted during production of the many Chinese-made goods they consume.

He also firmly rejected calls for global emissions caps across high-polluting industrial sectors, such as steel-making.

These are favored by Japan and some Western nations as a way of curbing emissions from developing nations without clamping down on more vulnerable sectors of the economy, but Yu said they were little more than an attack on China's competitiveness.

'You don't need to measure the efficiency level of a European country against the efficiency of a developing country. The result would be obvious. It would not be fair to use a so-called benchmark,' Yu said. 

Technology transfer is a particularly sore issue, with China frustrated by rich nations' attitude toward one element Beijing considers vital for any deal. Yu was dismissive of arguments that Western governments cannot mandate the transfer of patented technology held by companies.

'As national governments, once you make a commitment it is up to you to find the ways and tools to ensure that your commitments are met,' he said.

China argues it is owed help