Companies that manufacture or import products containing potentially harmful chemicals will face an expanded regulatory regime beginning in 2019, the South Korean environment ministry said.

Under the reworked Act on the Registration and Evaluation of Chemicals, a company that manufactures or imports 1 metric ton (2,205 pounds) or more of a chemical must pre-register the substance by June 30, 2019.

Like the European chemicals law, South Korea will then require companies to register their potentially “worst...