South Korea said Tuesday it will reopen its complaint at the World Trade Organization over Japan's tightened export controls on the country, rebuking Tokyo for not showing willingness to settle their ongoing trade dispute.

South Korea's Trade, Industry and Energy Ministry had given its Japanese counterpart until the end of May to respond to its calls for withdrawing the export curbs.

Japanese Foreign Minister Toshimitsu Motegi immediately expressed displeasure at the South Korean announcement, saying it was made unilaterally by Seoul.

The dispute over the export controls is one of many issues that have bedeviled bilateral ties and one that arose after a series of top court rulings in South Korea that ordered Japanese firms to compensate South Korean plaintiffs over wartime forced labor.

In July last year, Japan tightened controls on shipments to South Korea of three key materials that are critical for South Korea's chip and display-panel industries.

The following month, Japan removed South Korea from a "white list" of countries that enjoy minimum restrictions on buying goods that can be diverted for military use.

Of the July move, Tokyo said the tighter export rules were adopted after discovering "inappropriate" cases of export controls related to South Korea.

In September that year, South Korea took the dispute to the WTO, claiming the tightened policies were based on political considerations.

But Seoul suspended the process at the world trade body in November, after the two countries agreed to start consultations on export controls.

In mid-May, the South Korean ministry said Seoul had addressed all of the concerns raised by Tokyo related to its export controls, and gave Japan until Sunday to decide to withdraw the export curbs and communicate such a decision.

The ministry said Tuesday that because no progress was made to solve the dispute, it has decided to reopen the complaint with the WTO.

Calling the South Korean announcement regrettable, Motegi told a regular press conference that the two countries had been continuing discussions on the matter.

The Japanese minister reiterated that South Korea would need to make improvements to its own export controls for Japan to ease its measures.