"It is an indisputable fact that China mainly relies on coal for its overall energy structure. Such a structure will remain hard to change for a long time," Zhang Guobao, head of the National Energy Administration, told reporters.

China, which according to several groups of scientists is the world's worst emitter of greenhouse gases, relies on coal for nearly 70 percent of its energy needs.

In a speech at the United Nations this week, President Hu Jintao pledged to reduce the carbon intensity of China's economy by a "notable margin" by 2020 from their 2005 levels, but did not provide a figure.

Carbon intensity is the measure of greenhouse gas that is emitted per unit of economic activity.

Analysts say Hu's promise focuses on improving energy efficiency as China's economy grows, which could slow the growth of emissions -- but is not a guarantee that China's volume of carbon output will fall.

China and other developing nations have long resisted mandatory emission curbs as part of the next treaty on fighting climate change, which nations will try to hammer out in Copenhagen in December.

Zhang said the government would "go all out" to develop renewable energy sources to "reduce carbon emissions and energy consumption".

As an example of its efforts so far, China's installed wind power capacity was the fourth biggest in the world after increasing four-fold in the past three years to more than 12 gigawatts, Zhang said.

"I am confident that in the near future installed wind power capacity in China will be the first or second largest in the world," Zhang said.

China has committed in its current five-year plan to cutting energy consumption per unit of GDP by 20 percent between 2006 and 2010.

It also aims to get 10 percent of its power from renewable sources by 2010 and 15 percent by 2020.