South Korea’s Supreme Court last year ordered two Japanese companies to compensate the wartime workers in a ruling that Tokyo said violated international law. Japan believes the issue of compensation was settled under a 1965 treaty.
Japanese Foreign Minister Taro Kono plans to summon South Korea's ambassador on Friday, his ministry said, in a deepening political and economic row over compensation for Korean forced labourers in the World War Two era.
Kono will once again urge Seoul to take "appropriate steps" to rectify what Japan says was an improper ruling last year by South Korea's Supreme Court ordering two Japanese companies to compensate the wartime workers, public broadcaster NHK reported.
Japan says the decision violated international law because the issue of compensation was settled under a 1965 treaty which established diplomatic relations between the two nations post World War Two.
Compensation of South Koreans for labour during Japan’s 1910-45 occupation of the Korean peninsula has soured relations between the United States' closest Asian allies.
Things took a turn for the worse this month when Japan restricted exports of high-tech material to South Korea, a move that could threaten global supplies of microchips and smartphone displays.
Industry Minister Hiroshige Seko, in a seven-part tweet late Thursday, reiterated that Japan implemented the export curbs over South Korea's "deficiencies" in its export control systems and not in retaliation in the labourer's dispute.
He said not only had the labourers issue but "repeated negative movements" on the South Korean side had been weighing on relations between the countries.
The escalating row could have repercussions on the security front, as South Korea could reconsider its intelligence-sharing deal with Japan if the situation worsens, Yonhap reported.