WASHINGTON - The US Commerce Department on Wednesday launched anti-dumping and countervailing duty investigations against imports of fine denier polyester staple fiber from China, India, South Korea and Vietnam.

The investigations are a response to a request from three US-based producers of polyester staple fiber, the Commerce Department said in a statement.

They alleged that producers in each of these four countries were dumping fine denier polyester staple fiber in the US market with margins ranging from 21.43 percent to 103.06 percent.

They also claimed that the governments of China and India were providing improper subsidies to producers of polyester staple fiber, the department said.

The US International Trade Commission (ITC), another US trade authority, is scheduled to make its preliminary inquiry determinations around July 17.

The probe will continue if the ITC determines that there is a reasonable indication that imports of polyester staple fiber from these countries materially injure or threaten the domestic industry of the United States.

Last year, imports of denier polyester staple fiber from the Chinese mainland and China's Taiwan were estimated at about $79.4 million and $9.6 million, respectively, according to the department.

China's Ministry of Commerce has kept urging Washington to abide by its commitment against protectionism and help maintain a free, open and just international trade environment.