Victims of Japan's wartime forced labor during Japan's colonial rule and their families attend a press conference in front of the Supreme Court in Seoul, Jan. 25. Yonhap

The number of South Korean victims of Japan's wartime forced labor during its 1910-1945 colonial rule known to still be alive fell below 1,000, amid calls for prompt state efforts to document their stories.

According to government data released on Wednesday by the Association of Japan's Forced Labor Victims, a civic group, the number of such known survivors was 904 as of January, a decrease from 1,264 last year.

As most of them are in their 90s or older, the number has been falling sharply in recent years, from 9,937 in 2015 to 5,245 in 2018 and to 2,400 in 2021 before reaching the current level.

Under a law passed to support the victims, the government has provided each with 800,000 won ($600) for medical fees every year since 2009.

In a statement sent to reporters, the group called for expanding the amount of support.

"Most male victims who were forced to work as soldiers, military officials and other workers have come under hospital care as they are around 100 years old now," the group said.

"Women who were forced into sex slavery as teenagers are in their mid-90s … The size of government support should be expanded for medical costs and other practical measures to help the aging survivors."

The organization also called on officials to set up a system to document the tragic chapter of Korea's history based on their memories before it is too late.

"The central and local governments should step up efforts to collect their accounts, publish educational materials and establish a center for such records so they won't just die out and so that younger generations will be able to see the historical facts and know of their experiences," it said.