March 18 (Bloomberg) -- China’s top negotiator on climate change said a U.S. proposal to impose duties on imports with countries that don’t try to limit their carbon emissions was “an excuse to impose trade restrictions.”

Xie Zhenhua, the vice chairman of China’s National Development and Reform Commission, said he was “absolutely opposed” to a comment by Energy Secretary Steven Chu yesterday that tariffs should be considered “in order to protect American industries.” Chu, speaking before a congressional panel, said the duties would prevent U.S. companies from being at a disadvantage in competition with China and India.

Speaking to scholars, officials and reporters on a visit to Washington, Xie said such a policy would constitute protectionism under the guise of “climate protection.” Xie also said China was taking “active measures” to reduce its greenhouse-gas emissions.

President Barack Obama has set a goal of cutting carbon- dioxide emissions, which contribute to global warming, by 80 percent from 1990 levels by 2050. He supports a cap-and-trade system that would set limits on greenhouse-gas emissions and let companies trade pollution allowances on a market.

China and the U.S. are the world’s two biggest emitters of greenhouse gasses. Together they are responsible for 41 percent of the world’s carbon dioxide emissions, according to Senator Maria Cantwell, a Washington Democrat who appeared at today’s event with Xie.

To contact the reporter on this story: Michael Forsythe in Washington at mforsythe@bloomberg.net.

Last Updated: March 18, 2009 20:04 EDT