SEOUL -- The National Assembly voted Friday to designate Aug. 14 a day to honor wartime "comfort women," a move that could further strain South Korean relations with Japan.

Though not a holiday, the national and local governments will make efforts to promote it and hold events.

The law requires the government to raise awareness of the issue at home and abroad, as well as consult with survivors before adopting any policy affecting them and provide more financial assistance.

A former comfort woman went public with her experience for the first time in South Korea on Aug. 14, 1991. President Moon Jae-in's administration announced plans this July to make the date a day of commemoration.

Japan expressed its concerns over the comfort women day legislation, telling Seoul that the move would "throw cold water on efforts to foster future-oriented bilateral relations," Japanese Chief Cabinet Secretary Yoshihide Suga said at a news conference Friday.

Separately, the mayor of Osaka said Friday that he would seek to end a sister-city relationship with San Francisco, which had accepted a donation of a comfort woman statue from a South Korean advocacy group.

"This is very unfortunate," Hirofumi Yoshimura told reporters in Japan's third-largest city. "Our relationship of trust has been completely destroyed."

With additional reporting from Osaka.