Japan has protested to South Korea over a court order that forces Mitsubishi Heavy Industries Ltd. to sell assets in the country to provide compensation for wartime forced labor, Foreign Minister Toshimitsu Motegi said Tuesday.

"It is extremely regrettable. Liquidating (the assets) would invite a grave situation for both Japan and South Korea," Motegi told reporters following the South Korean court's decision on Monday that Mitsubishi must sell the assets, which were earlier seized by former plaintiffs in lieu of compensation in a lawsuit they won against the company.

It is the first time that a South Korean court has ordered the sale of a Japanese company's assets in relation to the issue. If the assets are actually liquidated, it will likely deal another blow to already frayed bilateral relations.