SEOUL -- At least 1,000 South Koreans who were forced to work for Japanese companies during World War Two plan to file the largest class-action suit of its kind for damages from their former employers.

More than 1,000 victims and bereaved families submitted applications to join class-action suit.

"After legal review, the suit will be filed with the Seoul Central District Court against 66 Japanese firms," Chang Duk-hwan, secretary general of the Asia Victims of the Pacific War Family of the Deceased Association of the Korea, said in a phone interview on Thursday.

According to Chang, 7.8 million Koreans were coerced to work for about 4,000 Japanese companies during the 1910-1945 Japanese colonial rule of the Korean Peninsula. The forced laborers were paid no wages though they performed dangerous tasks without being properly fed.

Most of the Japanese firms disappeared after the end of the World War Two, with only 66 firms, such as Mitsubishi, Mitsui, Aso and Nissan, still doing business.

Japanese companies have denied responsibility, insisting that the issue on damages for forced labor were resolved by a 1965 treaty, which normalized diplomatic ties between Seoul and Tokyo.

Defying those claims, the South Korean Supreme Court ruled in May 2012 that individual claims for damages still exist despite the 1965 treaty, triggering a wave of individual suits for damages from the Japanese firms.

In June 2014, the South Korean victims' association already filed a class-action suit, together with 252 victims and bereaved families, against the Japanese companies.

About five months later, four representatives of the association filed a class-action suit against the South Korean government.