South Koreans who say they or their family members were forced to work for Japanese companies during World War II have sued Japanese firms, including Mitsubishi Materials Corp., their lawyers said.

Also covered by the suits involving 54 plaintiffs, which were filed Monday, are Mitsubishi Heavy Industries Ltd., Nippon Coke & Engineering Co., Sumiseki Holdings Inc., Nippon Steel Corp., JX Nippon Mining & Metals Corp., Nachi-Fujikoshi Corp., Nishimatsu Construction Co. and Hitachi Zosen Corp.

The suits were filed at the district court in Gwangju. They follow a similar move earlier in April by 31 South Korean plaintiffs at a Seoul court against four Japanese companies, including Nippon Coke & Engineering, which was formerly Mitsui Mining Co.

The Gwangju court is likely to rule in favor of the plaintiffs, as the country’s courts have consistently ruled in favor of Korean plaintiffs since its top court in October ordered a Japanese company to compensate victims of forced labor during the war.

A Gwangju-based citizens group helping wartime laborers get compensation from Japanese companies solicited potential plaintiffs between March 25 and April 5, and processed paperwork for 537 cases, the lawyers said at a news conference in Gwangju on Monday.

“For the remaining people who could not participate this time, we plan to conduct thorough investigations for official proof of wartime labor” so there could be a second and third wave of suits, one of the lawyers said.

A South Korean court has indicated a range of periods during which additional suits can be filed, by making Oct. 30, the day of the landmark top court ruling, the start of a new period. The end of the shorter period is at the end of April, and the longer period ends three years from Oct. 30.

The 54 plaintiffs, of whom three are former laborers, are each seeking up to 100 million won (¥9.63 million) in compensation.

Japan claims that the issue of compensation arising from its 1910-1945 colonization of the Korean Peninsula was settled under a bilateral agreement signed when the two countries established diplomatic ties in 1965.