SEOUL -- South Korea's Supreme Court on Thursday ordered Mitsubishi Heavy Industries to pay compensation to two groups of South Koreans who were forced to work for the company during World War II.
The ruling comes a month after the court made a similar order against Nippon Steel & Sumitomo Metal -- a verdict that further strained the already fractious ties between Tokyo and Seoul.
Ties between the two U.S. allies were also damaged last week when South Korea dissolved a foundation created to assist wartime "comfort women" -- essentially gutting a 2015 deal with Japan to settle the issue. Relations have been chilly for decades over disputes stemming from Japan's occupation of the Korean Peninsula (1910-1945) and a lingering argument over the sovereignty of islands in the Sea of Japan.
One case involved five Koreans who were sent to work in a plant in Hiroshima. They claimed they were exposed to radiation in the 1945 atomic bombing of the city, and filed the lawsuit in 2000 in South Korea. The plaintiffs lost the first two trials at lower courts, but in 2012 the top court annulled the ruling at a second trial and demanded the case be re-examined.
The other case was filed by former five members of the Korean Women's Volunteer Labor Corps who worked at a Mitsubishi aircraft plant in Nagoya. A lower court in South Korea ordered the company to pay the women damages in 2015.
In a statement after the ruling, Mitsubishi Heavy said that Japan's Supreme Court has already issued a "final and binding judgment" to dismiss the two cases in 2007 and 2008. The company said "these rulings are deeply regrettable, as they violate the Agreement (in 1965) and are contrary to the view of the Japanese government."
Japanese Chief Cabinet Secretary Yoshihide Suga said Thursday that Japan is determined to take "various measures including going to an international trial and countermeasures in terms of protection of business activities of Japanese companies."
Tokyo has been insisting that Seoul take immediate steps to resolve the problem. After the Oct. 30 ruling against Nippon Steel, Foreign Minister Taro Kono summoned Lee Su-hoon, the South Korean ambassador to Japan, and made a strong protest against the judgment.
Tokyo insists that the issue of reparations to people forced to work was resolved in a 1965 treaty, in which the two countries normalized diplomatic relations.
However, South Korea's Supreme Court said in an Oct. 30 statement that "the treaty does not cover the right of the victims of forced labor to compensation for crimes against humanity committed by a Japanese company in direct connection with the Japanese government's illegal colonial rule and war of aggression against the Korean Peninsula."
South Korean Prime Minister Lee Nak-yeon and his team are considering what steps to take, and is expected to indicate what direction these will take by the year.
The ruling is the latest in a series of cases against Japanese companies. Also Thursday, the Seoul Central District Court dismissed an appeal by Nippon Steel over a previous ruling obliging it to pay former workers damages of 100 million won (about $90,000).
Nikkei staff writer Eri Sugiura in Tokyo contributed to this report.