China promised Monday to better control emissions of greenhouse gases, unveiling a new national program to combat global warming, but rejected mandatory caps on emissions as unfair to countries still trying to catch up with the developed West.

The program offered few new concrete targets for reducing emissions of the greenhouse gases that are believed to contribute to global warming. But the plan outlined steps China would take to meet a previously announced government goal of improving overall energy efficiency in 2010 by 20 percent over 2005's level.

One of China's chief objectives is "to make significant achievements in controlling greenhouse gas emissions," said the report, released by the National Development and Reform Commission, the economic planning agency.

Among the measures the government called for were stepped-up efforts to put the hard-charging but inefficient economy on a more sustainable footing, to research and deploy new energy-saving technologies and to plant more trees.

Given an economy that has been growing at better than 9 percent annually over the past 25 years, the plan's overall effect, if implemented, would be to slow the increase in greenhouse gases, not reduce their absolute amount.

China has fallen under increasing pressure internationally to take more forceful measures to curb releases of greenhouse gases. The country relies on coal among the dirtiest of fuels to meet two-thirds of its energy needs and is projected to surpass the U.S. as the world's No. 1 emitter of greenhouse gases sometimes in the next two years.

In explaining the new program, the head of China's planning agency said global warming was largely caused by 200 years of unrestrained industrialization by the West, and it would be unfair to impose mandatory emissions caps on China and other developing nations.

"This would hinder the development of developing countries and hamper their industrialization," Ma Kai told reporters.

The report's release seemed in part an attempt to pre-empt criticism of China when Chinese President Hu Jintao attends an expanded summit of the Group of Eight industrialized nations in Germany this Friday. The summit will feature a session on global warming.