WASHINGTON: The US Commerce Department said on Tuesday that it has set preliminary anti-dumping duties (AD) on imports of steel grating from China, a move that might escalate trade disputes between the two countries.

The department said it "preliminarily determined that Chinese producers/exporters have sold steel grating in the United States at 14.36 to 145.18 percent less than normal value."

As a result of this preliminary determination, Commerce will instruct US Customs and Border Protection to collect a cash deposit or bond based on these preliminary rates.

Those firms were Ningbo Jiulong Machinery Manufacturing Co Ltd, Sinosteel Yantai Steel Grating Co Ltd, Ningbo Haitian International Co Ltd/Ningbo Lihong Steel Grating Co Ltd and Yantai Xinke Steel Structure Co Ltd.

All other Chinese exporters or producers received an anti-dumping duty rate of 145.18 percent, the Commerce Department said.

From 2006 to 2008, imports of steel grating from China increased 538.44 percent by volume and were valued at an estimated 90.7 million ?dollars in 2008, according to the?Commerce Department.

Commerce said that it is currently scheduled to make its final determination in April 2010.

If Commerce makes an affirmative final determination, and the US International Trade Commission makes an affirmative final determination that imports of steel grating from China materially injures, or threaten material injury to, the domestic industry, Commerce will issue an antidumping duty order.

The new case followed US President Barack Obama's recent decision to impose punitive tariffs on all car and light truck tires from China for three years, a move quickly denounced by China as a "serious act of trade protectionism."

The protectionist moves by the Obama administration will ultimately hurt the US-China trade relations, which are becoming more and more important due to the global financial crisis, economists warned.