BEIJING (AP) — China is requiring importers of a U.S. industrial chemical to post deposits in preparation for possible anti-dumping duties amid rising trade tension with Washington.

The Ministry of Commerce said Tuesday in a preliminary ruling that styrene monomer from the United States, South Korea and Taiwan is being sold at prices 5 to 10.7 percent below the proper level.

Importers must now pay cash deposits while the ministry completes its investigation.

The ministry said in its ruling the Chinese styrene industry has been "substantially damaged" by dumping.

The decision follows U.S. President Donald Trump's approval last month of higher tariffs on Chinese-made solar equipment and washing machines that Washington said were sold at improperly low prices.

Styrene monomer is a basic material used in the plastics industry.