Main opposition Democratic Party of Korea Chairman Lee Jae-myung presides over a senior party meeting at the National Assembly in Seoul, Sept. 22. Yonhap

Opposition leader Lee Jae-myung on Friday slammed President Yoon Suk-yeol's alleged use of foul language, saying it is a disgrace that made people deeply mortified and hurt their dignity.

Yoon was caught on video making a remark privately to aides in New York on Wednesday that appeared to include vulgar words. Though the recording was not clear, many thought Yoon was talking about U.S. Congress and U.S. President Joe Biden

But Yoon's office later rejected the claim, explaining he was referring to how he would be embarrassed if Korea's opposition-controlled National Assembly rejected the $100 million he pledged to contribute to the Global Fund.

Despite the explanation, criticism ran high over Yoon's apparent use of vulgar language.

"It's a disgrace for the people, who must have felt deeply mortified and had their dignity hurt," said Lee, chair of the main opposition Democratic Party of Korea (DPK), during the party's Supreme Council meeting. "I'm at a loss for words. What else can I say?"