China's Ministry of Commerce (MOC) Saturday expressed "regret" over a U.S. government decision to investigate China's renewable energy policies, and said it would defend its interests in accordance with World Trade Organization (WTO) rules.

The U.S. Trade Representative's office started the investigation on Oct.15 in response to the United Steelworkers union's complaint on Sept. 9 that China's support for its renewable energy industries gave Chinese producers an unfair advantage over competitors.

The unilateral U.S. move, under a procedure called Section 301, could set the stage for retaliatory U.S. sanctions on Chinese goods if China does not change its policies.

"The union's complaint is groundless and irresponsible" as both parties should act in line with WTO rules, said an official with MOC's Bureau of Fair Trade for Imports and Exports in a statement.

While the world is working toward improving the environment for the welfare of human kind, the U.S. move sent the wrong signal that the U.S. did not support China's efforts to that effect, the official said.

The U.S. was subsidizing up to 2,300 energy-related programs, including clean-energy projects, which made the U.S. criticism of other country's environmental efforts unjustifiable, said the statement.

The U.S. should enhance collaboration with other countries in clean energy and meet climate and environment challenges together, said the statement.