In the first phase of the agreement, 39 industrial countries, including as Canada, Japan and members of the European Union, have agreed to cut emissions, recognizing that they are responsible for most of the heat-trapping gases already emitted.

Developing countries such as China, the world's second largest producer of greenhouse gases, and India do not have emissions caps in the first phase of the Kyoto pact, which lasts until 2012.

The United States, the world's top emitter of the gases, pulled out of the Kyoto pact in 2001, saying it unfairly left out rapidly developing nations and would hurt the economy.

Claude Mandil, executive director of the Paris-based International Energy Agency told reporters in Montreal China is interested in curbing emissions, but is wary about hurting its economy.

"So we imagine using something that is like a carrot, without a stick," Mandil said.

A "no lose" approach, he said, would set a target for emissions. If China surpasses the target, it would not be penalized. But if it came under the goal, it would be rewarded, perhaps by getting credits on an emissions trading program.

China says it needs to burn more fuel, such as coal and oil, to boost economic growth. Even so, its emissions per person are much lower than those of the United States. Chinese per capita emissions of carbon dioxide equivalent are 2.7 tonnes, against 20.1 tonnes per American.