The lawsuit comes as South Korean president Yoon Suk-yeol visits Tokyo in a bid to mend relations that have been marred for decades by the issue of Japan’s use of South Korean forced labour during World War Two.

Yoon has sought to break the impasse by dropping demands for compensation from Japan and proposing instead to use funds donated by South Korean companies, an idea opposed by some forced labour victims.

South Korea’s Supreme Court in 2018 ordered Mitsubishi Heavy to compensate the victims, but the company has not done so, with Japan arguing the matter was settled under a 1965 treaty.

Relations between the two countries, both important US allies in North Asia, have been dogged by the bitter legacy of Japan’s 1910-1945 occupation. The ties hit the lowest point after the 2018 court ruling.

The fresh lawsuit is part of efforts to speed up compensation payments from the proceeds of bonds owned by a South Korea affiliate of Mitsubishi Heavy, the representatives said in a statement, reiterating victims would not accept money from South Korean companies not connected to their abuse.