China has slammed a U.S. Department of Commerce investigation that believed Chinese state-subsidized plastic resin being imported into the United States.

Shen Danyang, spokesperson for China's Ministry of Commerce, accused the Department of Commerce of using "biased and discriminatory practices" after its preliminary determination that Chinese producers of polyethylene terephthalate imported into the United States had received subsidies of up to 18.88 percent from the Chinese government.

China hopes the final ruling, expected at the end of December, can be made in a "fair and balanced manner," Shen said at a press conference on Wednesday.

He also questioned another U.S. ruling in June that calculated high dumping margins and countervailable subsidies for Chinese tires.

Shen said this probe was also discriminatory and that the decision had greatly damaged the interests of Chinese enterprises. The spokesperson called on the United States to reverse its final ruling in the case to "protect economic relations."