Photo/Illutration Victims of wartime labor and their family members arrive at the Supreme Court in Seoul on Nov. 29, 2018. (AP file photo)

SEOUL--Colonial-era Korean laborers are seeking a court's approval for the sales of local assets of their former Japanese employer after it refused to comply with a court order to compensate them for wartime labor decades ago.

The development comes amid growing tensions between South Korea and Japan. Tokyo recently tightened controls on high-tech exports to South Korea, a move Seoul believes is retaliation for the South Korean court rulings last year. Japan says it is not retaliation.

Lawyers and supporters of the Koreans who worked for Mitsubishi Heavy Industries during Japan's 1910-45 occupation of Korea said in a joint statement Tuesday they'll soon ask a South Korean court to authorize the sales of some assets that South Korea has seized from Mitsubishi.

The assets are some of Mitsubishi's trademark rights and patents.

The lawyers and activists said the have sent three requests for negotiations on the compensation to Mitsubishi but it hasn't responded. Three of their aging plaintiffs died of old age this year, they said.

"We express our deep regret over the fact that our efforts to try to find a rational solution via dialogue for the development of South Korea-Japan ties have foundered repeatedly," their statement said.

If a court approves, Mitsubishi's assets will be put up for auction to raise funds to pay compensation to the former wartime laborers. The whole process is expected to take about six months, according to Kim Yeong Hwan, an activist with a group that signed the joint statement.

Such an approval would likely fan antagonisms between with Tokyo at a time when relations are already at their worst in decades.

South Korea has been stepping up pressure on Japan to withdraw the newly imposed trade controls, which require approvals for all sales of certain materials used in many high-tech products.

In his toughest comments yet on the issue, South Korean President Moon Jae-in said Monday the measure threatens to shatter economic cooperation between the neighbors and could damage Japan more than South Korea.

Japan says the three materials subject to its export control measure can only be sent to trustworthy trading partners. Japanese officials have suggested there may have been transfers of sensitive materials from South Korea to North Korea in a violation of U.N. sanctions on the North. Seoul has dismissed as groundless such a view and proposed a U.N. investigation on it.

The Japanese trade minister, Hiroshige Seko, rejected Moon's comments.

"From the beginning it was clearly stated that this review was for national security purposes, to appropriately implement export controls," Seko told reporters. "It has been consistently explained from the beginning that this is not a countermeasure and yesterday's remark from President Moon was not on point."

Seko said he did not expect Japanese companies to be harmed by the tighter export controls.

South Korea plans to file a complaint with the World Trade Organization and raise the issue at next week's WTO General Council in Geneva. Trade officials from the countries failed to resolve the dispute in a working-level meeting in Tokyo on Friday.