South Korea’s main opposition Democratic Party of Korea on Thursday accused President Yoon Suk Yeol of favoritism and unlawful interference in the 2022 by-election, disclosing a private call between Yoon and his former political consultant Myung Tae-kyun.

The party claims the recording reveals Yoon’s involvement in election matters while serving as the incumbent president.

In the May 2022 phone recording disclosed to media by the Democratic Party, Yoon, then the president-elect, told the People Power Party's Rep. Yoon Sang-hyun, who was in charge of selecting candidates to run for the 2022 election, that he insisted Kim Young-sun be nominated as a candidate.

This eventually laid the groundwork for Kim to become the National Assembly representative for Uichang-gu in Changwon, South Gyeongsang Province, in June 2022.

"I said to (the People Power Party's internal committee dedicated to a candidate selection) that Kim should be chosen because she worked hard for me since I vied for a post for a presidential nominee (of the People Power Party)," Yoon tells Myung in the recording.

Myung replies that he would "never forget (Yoon's) grace for good."

Rep. Park Chan-dae, floor leader of the Democratic Party, said this "confirms for the first time that President Yoon had interfered in the party's process of selecting who is running for a by-election in 2022" as a public official, adding that this alleged illegal action proves that a shady deal was in place.

Later on Thursday, a man named Kim Han-me filed a complaint against figures including Yoon, his wife Kim Keon Hee and Myung for their alleged violations of the Public Official Elections Act.

Under the law, public officials -- including the South Korean president -- who are to maintain political neutrality shall not exercise unreasonable influence over elections or perform any act likely to impact election results.

Former President Park Geun-hye was sentenced to two years of imprisonment in 2018 for violating the law. She was facing similar charges of interference in the Saenuri Party's candidate nomination for the 2016 general election, a year before she was impeached. The Saenuri Party was a precursor to the People Power Party.

Asked whether the main opposition party could accuse Yoon of illegal election meddling although he was a president-elect when the phone call took place, Rep. Noh Jong-myeon told reporters that their accusation was valid because the ruling party's decision was made on the day Yoon was inaugurated, on May 10, 2022.

Noh also said that Myung had let a person whose identity remains undisclosed hear the recorded phone call on June 15, 2022. Park of the Democratic Party said the party could guarantee the genuineness of the evidence, but declined to reveal how it obtained the recording.

Yoon's office on Thursday denied that Yoon as the president-elect communicated with the People Power Party's committee over the matter, adding that the party decided to nominate Kim Young-sun because of her competitive edge.

Yoon's office did not deny the phone conversation itself but said the conversation "was not memorable" and that Yoon was "trying to be nice" to Myung.

Rep. Yoon Sang-hyun of the ruling party, the then leader of the committee, told reporters that the committee had never discussed the ruling party's candidate nomination with the president-elect, adding such a thing was "impossible."

Rep. Joo Jin-woo of the People Power Party said that, should the allegations turn out to be true, Yoon stll cannot be criminally charged because Yoon was a president-elect at a time of the phone call, and because there is a legal precedent that found a president not guilty of expressing an opinion to a member of the ruling party's candidate nomination committee.

Kim, who won the by-election for a seat in the 21st National Assembly in June 2022, remained a lawmaker until May 2024. She was not nominated as the party's candidate for the April general election this year. She previously served four full terms.

This is a major development in an election meddling scandal involving Myung, President Yoon and his wife Kim Keon Hee.

Myung, who ran his own polling company, provided 81 presidential election predictions during Yoon's presidential election campaign in 2021 and 2022.

Earlier in September, a local news report indicated that Myung's private conversation with Yoon's wife indicated that she was aware that Myung was an intermediary seeking to help Kim Young-sun land the nomination in the by-election.

This followed an additional revelation by Kang Hye-kyung, who formerly worked at Myung's election forecast company, that some of the election predictions were not included in Yoon's campaigning expenses, and were later offset by first lady Kim's offer to nominate Kim Young-sun for the 2022 by-election. Kang later worked as the lawmaker's accountant.

Prosecutors estimate the true cost of all 81 predictions at 370 million won ($268,000), but suspect that a combined 240 million won was covered by two unnamed People Power Party members aspiring to become politicians in the 2022 local elections. They also suspect that Kim Young-sun helped reimburse those two members later on.

Meanwhile, South Korea's prosecution on Thursday raided Myung's residence in Changwon, South Gyeongsang Province, over his alleged violation of the Election Act.