Mitsubishi Heavy Industries, an H-2A rocket carrying the Hope Probe known as "Al-Amal" in Arabic, developed by the Mohammed Bin Rashid Space Center in the United Arab Emirates to explore Mars, blasts off from Tanegashima Space Center in southwestern Japan on Monday. Photo: AFP

Japan has protested a South Korean court order that assets seized from Mitsubishi Heavy Industries be sold off to pay compensation to two women subjected to forced labor for the company during Japan's occupation of the Korean Peninsula.

A support group for the South Korean forced labor victims welcomed the court decision as a "step forward" on compensation.

 However, top Japanese officials warned of serious impacts to already strained diplomatic ties.

Japan's Foreign Minister Toshimitsu Motegi said on Tuesday the ruling a day earlier Japan warns of "serious" impact after South Korean forced labor verdict by the Daejeon District Court in South Korea was a "clear violation of international law."

"We must avoid serious impacts on Japan-South Korea relations," Motegi said, describing the court's decision as "truly regrettable" during a regular news conference in Tokyo.

Motegi said Japan called upon the vice consul at the South Korean Embassy in Tokyo to protest the verdict, while Mitsubishi Heavy said it would appeal the court decision.

The Daejeon court was not immediately available for comment requested by Reuters.

Relations between the two countries, both important US allies in North Asia, have been dogged by the bitter legacy of Japan's 1910-45 occupation.

Disagreements over recent rulings related to wartime forced labor, including in brothels, have been followed by a dispute over export controls which has yet to be resolved.

The two women, Yang Geum-deok and Kim Sung-joo, worked at a Mitsubishi aircraft factory in Nagoya, Japan when they were teens during World War II. 

The compensation for each woman was estimated at around $178,023.