China will take necessary measures to ensure Chinese aluminum companies' legal rights, the Ministry of Commerce said on Wednesday after the United States government launched its first self-initiated, anti-dumping and countervailing duty cases in 25 years.

The ministry's announcement came after the US Commerce Department launched the investigations on Tuesday covering more than $600 million worth of imports of common alloy aluminum sheet from China.

Wang Hejun, head of the trade remedy and investigation bureau at the Ministry of Commerce, said such anti-dumping duty investigations against the aluminum sheet that China exports are the first such actions initiated by the US Department of Commerce instead of a US industrial association in a quarter-century.

"It is a rare case in the history of international trade and has sparked strong dissatisfaction in China," he said.

The US claims that "some evidence shows Chinese manufacturers are shipping aluminum sheet to the country at prices that are lower than fair value and that the Chinese government is providing unfair subsidies to factories of aluminum sheet", Wang said.

"The aluminum industries in the two countries are complementary to each other and trade in such products is two-way," he said. "Disturbing routine trade activities in aluminum will harm the interests of both sides."

Chinese demand for aluminum is more than half of global demand at an estimated 60 million metric tons this year, according to the London-based the International Aluminum Institute.

This is the third case of trade friction between China and the US this month.

The US Commerce Department released its final ruling on Nov 13 on the anti-dumping and countervailing investigations against plywood imported from China, setting a 183.36 percent dumping margin and a subsidy range for Chinese companies of between 22.98 percent and 194.90 percent. A dumping margin is the amount by which the normal value is determined to exceed the export price of merchandise.

On Nov 23, the US Commerce Department also announced that certain tool chests and cabinets from China had a subsidy range of 14.03 percent to 95.56 percent. It ordered US Customs and Border Protection to collect cash deposits from importers.

Gao Peiyong, director of the Institute of Economics at the Chinese Academy of Social Sciences in Beijing, said, "US manufacturing businesses not only accounted for the most profitable sectors but also a number of segments with the highest industrial value added. They also diverted low-end segments to global markets."