The presidential office has sued the main opposition Democratic Party spokesperson for defaming first lady Kim Keon Hee over her alleged involvement in stock manipulation.

Spokesperson Kim Eui-kyeom earlier claimed that the first lady was involved in a so-called "pump and dump" scam involving Woori Technology shares listed on Kosdaq, South Korea's tech-heavy secondary bourse, in addition to her alleged involvement in stock manipulation of Deutsche Motors. "Pump-and-dump" schemes involve artificially inflating stock prices by spreading misleading information and then selling shares at the higher price.

The opposition spokesman also claimed that some prosecutors handling the case on first lady's alleged manipulation of Deutsche Motors had recently been demoted.

"The allegation that Woori Technology was involved in a pump-and-dump scheme is groundless,” the presidential office said in a written statement released Monday. “The case has never been reported to or investigated by the Financial Supervisory Service and it is not even on trial.”

The fact of the president’s spouse trading stocks 13 years ago cannot be described as stock manipulation without any evidence, the office said.

Following the news that the presidential office would sue Kim, the lawmaker said he "welcomes" the move with "open arms" and that “this is a good opportunity to investigate Kim Keon Hee properly.”

“If the presidential office is to accuse and punish me, the role of Kim Keon Hee in relation to Deutsche Motors and Woori Technology must be identified first,” he said on his Facebook account.

Kim said it is difficult to “believe in fairness” of the police investigation accusing the law enforcement agency for submitting itself under the command of the prosecution filled with President Yoon Suk Yeol's subordinates.

He asked the first lady to have a special prosecution if she finds it "unfair."

“If my argument turns out to be wrong, I will gladly accept any punishment,” he said.

The presidential office said in the morning it would file a complaint with the Seoul Metropolitan Police at 3 p.m. It said Kim’s "false" claim that President Yoon had a drinking party with his subordinates at Cheongdam-dong in Seoul last year was not included in the complaint because the case is currently under investigation.