Democratic Party of Korea Chairman Rep. Lee Jae-myung appeared Thursday for his fourth interrogation by prosecutors since his presidential election rival Yoon Suk Yeol took office, accusing the conservative government of attacking democracy.

It was the leader of South Korea's main opposition party's first time appearing for questioning regarding allegations of his involvement in a land corruption scandal that took place in 2015 in Baekhyeon-dong, an affluent district of Bundang-gu in Seongnam, Gyeonggi Province, during his tenure as the mayor of the city.

Calling the investigation highly political, Lee said the prosecution's probe was fabricated and is intended to incite social divide and conflict by seeking to arrest him.

While pledging to "fight against the Yoon administration," Lee reiterated that he would forfeit his immunity from arrest as a lawmaker, as the prosecution's seeking of an arrest warrant against him during the parliamentary sessions would disturb the Assembly. An arrest of an incumbent member of the parliament requires a majority approval.

He also claimed that he "has never gotten any private gain during (his) time on power while serving for the public."

Lee reportedly declined to make any verbal statement during the prosecutorial interrogation, other than the 30-page written statement.

Lee, formerly a lawyer, served as mayor of Seongnam from 2010 to 2018 and as governor of Gyeonggi Province from 2018 to 2021. He lost to Yoon in last year's presidential election, but became a lawmaker representing a constituency in Incheon in a by-election the same year, despite being suspected of multiple crimes.

Lee previously appeared at the prosecution office for interrogation over bribery charges involving a soccer club in January.

Lee was accused of soliciting at least 13.3 billion won ($9.9 million) in contributions to Seongnam FC from four companies while serving as the mayor of Seongnam, in return for land use deregulation, and disguising a 4 billion won bribe by one of the four companies as a contribution. Seongnam City was the owner of the club at the time.

A motion to allow the prosecution to arrest Lee was voted down by the National Assembly -- controlled by the main opposition Democratic Party -- in February, allowing him to stand trial without being arrested.

He also faces charges related to a corruption scandal surrounding another construction project, in Daejang-dong in southern Gyeonggi Province.

He is suspected of a breach of trust by denying a state-run developer 489.5 billion won in financial gains, and allowing other developers -- including inexperienced asset management company Hwacheon Daeyu -- to profit improperly from the project. Private firms are claimed to have made 788.6 billion won in illicit gains and dividends that did not match the shareholding structure of the residential development consortium to which both the state-run developer and Hwacheon Daeyu belonged.

Lee also allegedly violated a corruption prevention law by allowing private companies to take 21.1 billion won in gains.

Lee has been on trial in the Daejang-dong and Seongnam FC cases, but has not been detained. Lee denied all the charges, given that the "advertising expenses" for Seongnam FC was in the public interest, not for himself, and that he had not taken any private gains from land corruption scandals in projects in Daejang-dong and in Wirye New Town, both in Gyeonggi Province.

Lee is also standing trial on charges of violating the election law by spreading false information. Lee said in an interview during the election campaign in December 2021 that he did not know a deceased suspect from a state-run company dedicated to land development in Daejang-dong. The prosecution believes it can prove otherwise, citing a photo of the two posing together.

In addition, prosecutors are also looking into the possible involvement of Lee, then Gyeonggi Province governor, in Korean underwear maker Ssangbangwool's illicit money transfer to high-ranking North Korean officials over the company's potential project in North Korea under the auspices of Gyeonggi Province.

Lee is not the only Democratic Party figure under investigation.

Prosecutors raided the office of a key figure Thursday, in connection with a scandal in which at least 94 million won in cash is believed to have been distributed to party members without proper bookkeeping. Prosecutors believe the cash was used to help former lawmaker Song Young-gil get elected as a party leader in the Democratic Party convention.

One of the main opposition lawmakers, Rep. Youn Kwan-suk, was arrested by the prosecution earlier in August over his involvement in the scandal.

Lee succeeded Song as the party chairman in August 2022.