Xie Zhenhua, head of China's Climate Change and Coordinating Committee, attends the UN climate change conference in Poznan, Poland, December 11, 2008. [Agencies]

China's top climate change official rejected as protectionist on Wednesday a US idea to put tariffs on some imports from countries that do not place a price on carbon, chiding the United States to do more to cut its greenhouse gas emissions.

US Energy Secretary Steven Chu on Tuesday told a congressional panel that once Washington develops a system limiting carbon emissions, if other countries do not impose a cost on carbon emissions the United States will be at a disadvantage.

Chu told the House of Representatives Science and Technology Committee that the tax idea was just one proposal the Obama administration should evaluate. He voiced hope that fast-growing developing countries such as China and India would take steps to reduce their emissions.

But Xie Zhenhua, head of China's Climate Change and Coordinating Committee said, "Climate change and charging carbon taxes in imports ... are two issues in two areas" and should be tackled in separate negotiating forums.

"I oppose using climate change as an excuse to practice protectionism on trade," Xie, a former Chinese environment minister, told the Carnegie Endowment for International Peace, a Washington think tank.

Earlier this week, Gao Li, director of China's Department of Climate Change, said countries that buy Chinese goods should be held responsible for the carbon dioxide emitted by the factories that make them in any global plan to reduce greenhouse gases.

Unlike the United States, China joined the Kyoto Protocol but is not required to cut its emissions because it is a developing country.

China's greenhouse gas emissions are now thought to be around the levels of those in the United States, which has led the world in emissions.

But Xie, who said he held fruitful consultations with Chu and other Obama administration officials, rejected the premise that China was a laggard in tackling emissions of greenhouse gases.

"China is not a country that does nothing," he said. "On the contrary we have done a lot," said Xie, who listed a set of market-based measures on pricing, taxes and financial incentives China was using to cut its emissions.

"The United States is in the same boat. They just talk about it but there are no actions, and we don't even know whether Congress will pass it," he said.

US President Barack Obama is pushing Congress to develop a system that would cap carbon emissions and require companies to purchase permits to release greenhouse gases. But some US lawmakers have raised concerns about how a cap and trade program would hurt an economy already in recession.

Pressure is rising on nations to seal a broader and tougher framework to replace the Kyoto Protocol on climate change in December during UN-led talks in the Danish capital, Copenhagen.