A civic group supporting South Korean plaintiffs who secured a ruling against Nippon Steel & Sumitomo Metal Corp. over wartime forced labor has said it will proceed with steps to seize the steel giant's South Korean assets after the firm ignored a Dec. 24 deadline.

The Japanese firm was ordered by South Korea's Supreme Court in October to pay 400 million won (about $350,000) to four South Koreans over forced labor during Japanese colonial rule between 1910 and 1945.

Lawyers for the plaintiffs earlier set a Dec. 24 deadline for the firm to respond to their request to begin talks on compensation, based on the ruling, but the firm did not do so.

"As the company failed to meet the deadline for taking action, which was 5 p.m. of Dec. 24, we will soon work on compulsory execution upon it," the Center for Historical Truth and Justice, the main group supporting the plaintiffs, said in a statement on Monday.

"However, we will also consider the fact that talks between authorities between South Korea and Japan are ongoing when deciding the exact date" of seizure, the group added.

To avoid such asset seizures, Japanese and South Korean Foreign Ministry officials have been holding working-level talks in Seoul.

Tokyo maintains that the issue of compensation in such cases was settled "completely and finally" in an agreement attached to a 1965 treaty that normalized ties between Japan and South Korea.