Prime Minister Shinzo Abe urged Seoul on Thursday to take steps to ensure a court ruling ordering compensation for wartime forced labor does not affect Japanese businesses and indicated that Tokyo would take the case to the international stage if necessary.

"To manage difficult issues between the two countries, South Korea's efforts are indispensable. We strongly expect the South Korean government to take positive measures against the ruling," Abe said during a session of the House of Representatives' Budget Committee.

South Korea's Supreme Court on Tuesday upheld a lower court decision that ordered Nippon Steel & Sumitomo Metal Corp. to compensate four South Koreans who were victims of forced labor during Japanese colonial rule from 1910 to 1945.

Calling the ruling an "unbelievable judgment," Abe said, "We will take resolute action with an eye on all possible options, including international adjudication." He suggested Tokyo could take the case to the International Court of Justice.

The Japanese government maintains that the right to seek compensation was terminated under a 1965 bilateral treaty stipulating issues relating to property and claims between the two countries and their peoples had been settled "completely and finally."

Tuesday's top court ruling could pour cold water on improving relations between Japan and South Korea, which need to work together in dealing with North Korea. Abe and South Korean President Moon Jae In visited each other's countries earlier this year.

Bilateral ties have often been rocked by issues related to territory and history, including Korean women who were forced to work in Japanese wartime military brothels.

Abe expressed his "deep regret" over a series of recent events that "run counter to efforts to build forward-looking bilateral ties."

He cited as examples South Korea's request for Japanese Self-Defense Force vessels not to fly the rising sun flag, used during World War II, in an international naval review and a recent visit by South Korean lawmakers to Seoul-controlled islets claimed by Tokyo in the Sea of Japan.

During phone talks on Wednesday, Japanese Foreign Minister Taro Kono requested his South Korean counterpart, Kang Kyung Wha, to take measures so that Japanese nationals and companies are not subjected to detrimental treatment as a result of the ruling.

The government has started contacting Japanese companies involved in similar lawsuits in South Korea to seek understanding over its stance that they should not abide by rulings upholding individual compensation claims by South Koreans, sources close to the matter said.

A senior Foreign Ministry official told a meeting of the ruling Liberal Democratic Party on Wednesday, "If even one Japanese company abides by (a compensation order), it would make no sense."

The LDP on Thursday adopted a resolution urging the government to study countermeasures, including taking the case to the ICJ.

In South Korea, 14 similar suits have been filed against Japanese companies, including Mitsubishi Heavy Industries Ltd., Nachi-Fujikoshi Corp. and Hitachi Zosen Corp.

South Korea top court orders Japan firm to compensate for forced labor