In July, Japan imposed tighter controls on exports of three materials to South Korea used in smartphone chips and displays following a diplomatic row over compensation for forced labourers during Japan's occupation of Korea during World War Two. The materials affected by Japan's export controls are fluorinated polyimides, photoresists and hydrogen fluoride, which are used by South Korean tech firms such as Samsung Electronics.

Under WTO rules, South Korea and Japan should meet within 30 days and if these talks fail, South Korea can request adjudication by a dispute settlement panel.

(Reporting by Stephanie Nebehay, editing by Louise Heavens)