The government on Tuesday expressed concern over South Korea's plan to install a monument on the grounds of a national cemetery for "comfort women," who were forced to work in Japanese wartime military brothels before and during World War II.

Chief Cabinet Secretary Yoshihide Suga said doing so would run counter to the spirit of a 2015 agreement under which the nations said they had "finally and irreversibly" settled the dispute.

The plan "could throw cold water on efforts made by both Japan and South Korea to develop a future-oriented relationship," Suga told a news conference, adding that Tokyo has relayed its concern to Seoul.

South Korea's Ministry of Gender Equality and Family said Monday the installation of the monument at the cemetery in the city of Cheonan, the first to be set up by the government in memory of comfort women, is aimed at raising awareness of the issue.

The monument will be completed later this year and unveiled at a ceremony on June 6 next year, the Korean Memorial Day meant to honor people who have contributed to the country, according to the ministry.

The Korean Peninsula was under Japanese colonial rule from 1910 to 1945 and many Koreans were forced into sexual servitude as comfort women.