BEIJING -- The Chinese Ministry of Commerce has labelled US anti-dumping and countervailing duty investigations into steel plates from countries and regions including China "imprudent" and blamed protectionism for the troubles of American steel.

"The United States has recently taken a series of trade remedy measures against steel exports from other countries and regions. Such acts are imprudent and cannot help US steel businesses solve their problems," the ministry said in a statement on Saturday.

"After more than three decades of protection and subsidies, the United States has distorted competition in its domestic steel market, deprived local companies of motivation to increase investment or improve technology and subsequently blunted their competitive edge," it said.

Against a backdrop of global slowdown and overcapacity, countries should cooperate more, follow WTO rules and promote free trade, rather than resorting to protectionism, according to the statement.

China encourages its companies to respond to the US investigations according to law. "We will closely watch the case and will use WTO rules to safeguard the rights and interests of Chinese companies," the ministry vowed.

The United States has said in a preliminary ruling that certain carbon and alloy steel cut-to-length plate from 12 countries and regions including China had substantially harmed the US steel industry.

The move came shortly after the US Commerce Department set final anti-dumping duties of 265.79 percent and anti-subsidy duties of 256.44 percent on imports of cold-rolled flat steel from China.