The central government may seize South Korean assets in Japan if the holdings of Japanese firms in South Korea are confiscated following recent Supreme Court rulings against them over the issue of wartime labor, sources have said.

The possible countermeasure is being discussed as a “last resort” by some in the government, the sources added.

The seizure of South Korean assets could be allowed as a measure of “diplomatic protection” under international law but would first need a related domestic law, they said.

On Oct. 30, the top South Korean court ordered Nippon Steel & Sumitomo Metal Corp. to pay compensation to South Korean plaintiffs who say they were forced to work for the company’s predecessor before the end of World War II.

On Thursday, it issued a similar ruling against Mitsubishi Heavy Industries Ltd.

Tokyo believes that the rulings contradict a 1965 bilateral agreement that declared the issue of rights over war-related claims was fully resolved. It may take the case to the International Court of Justice.

“We’re looking at every possible option,” Chief Cabinet Secretary Yoshihide Suga told a news conference Friday.

Foreign Minister Taro Kono, at a separate news conference, urged the South Korean government to promptly take appropriate action in the wake of the rulings.