Cancun, Mexico: Clashes between rich and developing nations over the future of the Kyoto Protocol for fighting global warming clouded UN climate talks on Saturday despite glimmers of progress in some areas.

“I urge you to look for compromise," Mexican foreign minister Patricia Espinosa told negotiators at the 189-nation talks that seek a modest package of measures to slow climate change.

Wrangling over whether to extend Kyoto, which obliges almost 40 developed nations to cut greenhouse emissions until 2012, overshadowed a review of work halfway through the talks that end on 10 December.

Extending Kyoto “is indeed the cornerstone of a successful outcome in Cancun," said Abdulla Alsaidi of Yemen, who chairs the group of developing nations at the talks, meant to avert more floods, droughts, desertification and rising sea levels.

Chinese delegate Su Wei said an extension of Kyoto was an “indispensable element" of a deal. Countries, including Bolivia, Venezuela and small island states, also criticized wealthy states.

Developing nations note that Kyoto imposes a legal obligation on its supporters to extend the pact. But Kyoto backers — especially Japan, Canada and Russia -- want a new, broader treaty that also binds emerging economies to act.

“We need a new, legally binding instrument with the participation of all major emitters," said Japan’s Mitsuo Sakaba. One UN official said a compromise would have to be found in “shades of gray between the two extremes.

New order

Climate talks are a test of a new, shifting world order where China’s strong growth has propelled it past the United States to become the world’s top emitter of greenhouse gases stoking global warming and past Japan to become the second biggest economy. Many developed nations are struggling with budget cuts and high unemployment.

The United States never ratified Kyoto, saying it would cost US jobs and wrongly omitted developing nations. That decision is also at the heart of Kyoto nations’ reluctance to extend the protocal unilaterally with no guarantee of action by Washington.

All nations say a treaty is out of reach after world leaders failed to reach a binding deal last year at a summit in Copenhagen.

Still, there were some signs of progress in narrowing other differences, such as elements of how to share green technologies worldwide, delegates said.

The talks are also trying to agree on a new fund to channel aid to poor nations and ways to protect tropical forests.

“Progress has been made in some areas but there areas where parties are still holding to national positions and even some areas going backwards in important issues," said Margaret Mukahanana-Sangarwe of Zimbabwe, chair of one session.

Away from the deadlocked government talks, business leaders sought new ways to help shift to a greener economy. Corporate executives said governments should legislate energy-efficiency targets to help cut consumption in buildings, power plants and vehicles.

“Solar may be sexy but energy efficiency is the gift that keeps on giving," said Adam Muellerweiss, commercial director of energy and climate change for Dow Chemical Co.

Espinosa said she would brief about 60 environment ministers on Sunday about her hopes for ending the deadlock.

In an earlier session, the United States and some developing nations criticized a separate UN draft text outlining long-term actions by all countries to slow global warming.