Japan says its tightened controls on the export of high-tech materials to South Korea are in line with World Trade Organization rules.
Japanese government officials plan to defend the restrictions at a WTO meeting that began in Geneva on Monday.
South Korea intends to raise the issue during the conference. Seoul is likely to tell WTO officials that Japan's move runs counter to international trade rules.
Japan's government has said the measure is necessary to ensure national security. The government said it had found "multiple cases of improper trade-related management by South Korea." Tokyo says the materials in question could be used for military purposes.
Seoul argues that the move violates the WTO's rules. But Japan says such restrictions are allowed on national security grounds.