SEOUL — Lawyers for South Korean plaintiffs who won a wartime labor compensation case against Mitsubishi Heavy Industries Ltd. said Tuesday that they will soon ask a court to authorize the sale of the Japanese manufacturer’s assets seized in South Korea.

South Korean court rulings last autumn ordering Japanese firms, including Mitsubishi Heavy, to pay damages to victims of forced labor during World War II have sent bilateral ties to their lowest point in years, with the envisioned asset sale seen in Japan as a real flashpoint.

The lawyers had set Monday as the deadline for Mitsubishi Heavy to agree to compensation talks, but the deadline passed with “no response or action from the company,” they said in a statement.

“Being over 90 years of age, the plaintiffs cannot delay legally stipulated procedures any longer,” the lawyers said.

The lawyers said they will file a request in the coming days for sale of the seized assets to secure compensation money.

In Tokyo, Japanese Foreign Minister Taro Kono urged the South Korean government not to allow the asset sale, saying that “we would need to take necessary measures if actual harm comes to Japanese companies.”

“We strongly urge them to make sure it doesn’t come to that,” he told reporters.

The South Korean Supreme Court in November ordered Mitsubishi Heavy to compensate two groups of South Koreans for forced labor at its factories in Japan during the war.

The plaintiffs included Korean women who had been recruited to work at factories in Japan near the end of the war, when the Korean Peninsula was still under Japanese colonial rule. The women, who included teenagers, were called members of the Korean Women’s Volunteer Labor Corps.

The company has refused to comply with the order, however, as Japan has taken the position that the issue of claims stemming from the 1910-1945 colonization was “settled completely and finally” under a 1965 bilateral accord signed alongside a treaty that established diplomatic ties.

For settlement of ongoing disputes over compensation, Japan suggested having third-party arbitration, setting a deadline of July 18 for response from South Korea.

A high-ranking official from South Korea’s presidential office, however, made it clear on Tuesday that the government would not accept Japan’s proposal as it is not what the plaintiffs want.

“If the surviving victims do not want it, it can’t be even mulled over as an option,” the official told reporters.

Two other companies — Nippon Steel Corp. and Nachi-Fujikoshi Corp. — have had their assets seized in South Korea following court orders to compensate South Korean plaintiffs over wartime labor.

Lawyers for plaintiffs in the cases against two companies have already asked courts to approve the sale of their assets seized in South Korea.

A local court in March approved the seizure of Mitsubishi Heavy’s assets in South Korea presumed to be worth about 800 million won ($678,300) that the lawyers for the plaintiffs say should cover compensation for four of them.

The seized assets include some trademarks and patents held by Mitsubishi Heavy in South Korea.