The Supreme Court upheld a lower court's acquittal of a former university professor on defamation charges regarding his comment that the Japanese military's mobilization of women for sexual slavery during World War II was a "type of prostitution."

The top court on Thursday confirmed the acquittal of Lew Seok-choon from defamation charges concerning the sexual slavery victims, saying there was no misunderstanding of the legal principle in the lower court ruling.

The court also upheld a lower court conviction of Lew on charges of defamation regarding a comment that the victims were trained by an advocacy group to falsely testify that they were forced into sexual enslavement by the Japanese military.

Lew was previously ordered a fine of two million won, or around one-thousand-400 U.S. dollars on the conviction.

Lew was indicted after making a statement to that effect during a sociology class in September 2019 that the wartime sexual enslavement was a form of prostitution.

The first trial acquitted the former professor from defamation against the victims, citing a constitutionally guaranteed freedom of academia and that he had shared a personal view during a debate, which was upheld in an appeal.

The Korean Council for Justice and Remembrance for the Issues of Military Sexual Slavery by Japan issued a statement, expressing strong regret over Thursday's decision.