BEIJING - Chinese President Hu Jintao has told his U.S. counterpart Barack Obama that closer cooperation on fighting climate change could help improve overall ties between the world's top two greenhouse gas polluters.

Hu also said he was optimistic about U.N.-led talks on a new global framework to tackle climate change, even though the latest round of negotiations ran into trouble.

Developing cooperation between the two sides on climate change issues would not only benefit the international community in its efforts to tackle climate change, but also have great significance for promoting the development of China-U.S. ties, the official Xinhua news agency quoted Hu as saying.

The leaders spoke by telephone on Wednesday morning Beijing time. Hu said the two sides face common challenges in the field of climate change, and shared common interests.

Obama is due to make his first presidential visit to China next month, when he will also attend the APEC regional summit in Singapore and visit Japan and South Korea.

Officials have touted climate change as an area where both sides have much to gain from working together and much to lose if they cannot reach a deal to limit the production of gases that scientists say are warming the atmosphere.

Beijing and Washington also face contention over trade, military plans, and human rights -- all issues likely to be discussed when Hu sits down with Obama in Beijing.

OVERALL TALKS COULD HELP PRODUCE CLIMATE AGREEMENT

But potential give-and-take across these issues may also help create room for some agreement on climate change, said Wang Ke, an expert on global warming at Beijing's Renmin University.

China may be able to make more concessions over climate change if it feels it's gaining more in other areas of the relationship, such as trade, Wang told Reuters.

Balancing across a whole range of issues may be easier than trying for a one-dimensional agreement on climate change.

China and the United States together account for about 40 percent of the world's greenhouse gas emissions, but China's average emissions per person are much lower.

In 2008, fast-growing China's emissions of carbon dioxide reached 6.8 billion tonnes, an increase of 178 percent over 1990 levels, according to the IWR, a German energy institute. U.S. emissions rose 17 percent to 6.4 billion tonnes.

Chinese scientists say higher global temperatures will cause more flooding in the south, droughts in the north and smaller harvests.

But despite growing concern among politicians and the public of many countries, U.N. climate talks on expanding the fight against global warming have largely stalled, making the outcome of a climate summit in Copenhagen in December uncertain.

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