BEIJING—China will impose a "margin ratio" of between 12.5 percent and 222 percent on imports of EPDM originating in the U.S., South Korea and European Union, China's ministry of commerce said.

The measure, set to take effect Oct. 28, follows a preliminary ruling in an anti-dumping investigation into supply of the synthetic rubber from the countries and region.

The investigation found that the EPDM imports were dumped, causing "substantial injury" to domestic industries.

The market probe was conducted "in strict accordance with the relevant laws and regulations of China and the relevant rules of the WTO," according to a statement.