The family of the late former President Roh Moo-hyun filed a libel suit, Monday, against Rep. Chung Jin-suk of the largest conservative Liberty Korea Party (LKP) over his claims last week that Roh committed suicide after quarreling with his wife.

The allegation by Chung, a former aide to ex-President Lee Myung-bak, prompted uproar among liberal politicians.

Roh Geon-ho, son of the late President Roh Moo-hyun, appears at the Seoul Central District Prosecutors' Office, Monday, to submit a complaint against Rep. Chung Jin-suk of the largest conservative Liberty Korea Party for libeling his father. Chung wrote on Facebook last week that Roh and his wife, Kwon Yang-sook, had a quarrel just before Roh committed suicide in 2009, and Kwon ran away from home. / Yonhap

The ruling Democratic Party of Korea (DPK) claimed Chung is raising a groundless allegation in order to defend Lee from an ongoing investigation into state-perpetrated irregularities committed under the Lee administration (2008-2013). Chung was Lee's chief secretary for political affairs from 2010 to 2011.

Chung wrote on Facebook on Sept. 20 that Roh committed suicide in 2009 due to a quarrel he had with his wife, Kwon Yang-sook, after Kwon and their son were questioned by prosecutors over allegations that they received bribes worth millions of dollars from former businessman, Park Yeon-Cha. Chung also said Kwon ran away from home after the quarrel.

Regarding Roh's death, liberals have claimed the conservative president unfairly targeted his liberal predecessor in an act of political retaliation, while conservatives said the bribe allegations involving Roh's family still need to be unearthed.

"Chung's blunt remarks are hurting the people," DPK Chairwoman Rep. Choo Mi-ae said at a party meeting, Monday. "But the people will see through his intentions and will not fall prey to his stratagem."

Rep. Park Nam-choon called on the party to take legal action promptly against Chung, saying his remarks cannot be forgotten even after he expressed regret.

"Conservatives have politically used the late Roh whenever wrongdoings of the conservative governments were disclosed," Park said. "Such impure attitudes are not acceptable. They should take legal responsibility."

Chung made the controversial remarks while state prosecutors are investigating allegations that the National Intelligence Service (NIS) attempted to exercise influence on public broadcasting under the Lee administration through detailed plans including personnel intervention.

The NIS's in-house reform committee, set up under the Moon Jae-in administration, handed over relevant documents to the prosecution on Sept. 14 and requested the investigation. Moon was Roh's chief of staff.

Expectations have been growing that Lee could be the subject of such a probe.

Separately, Seoul Mayor Park Won-soon filed a complaint with the prosecution against Lee, Sept. 19, accusing him of defamation and abuse of power. Park claimed the NIS systematically conducted illegal surveillance on him and spread groundless rumors about him and his family during the Lee administration.

As the controversy grew, Chung wrote on Facebook again on Sept. 23, expressing regret over the criticism regarding his earlier post.

"I did not intend to hurt the late Roh or his family," he said, claiming the Moon administration is unfairly targeting the Lee government in another act of political retaliation "to resolve Roh's deep sorrow."

The DPK members said Chung's explanation only served to deepen the controversy, saying he de facto admitted that Lee retaliated by orchestrating the 2009 investigation by the prosecution against Roh.

Citing that the LKP is currently calling on the prosecution to investigate the bribe allegations involving Roh's family again, the DPK members also said Chung and the LKP are trying to water down the controversy over the alleged unlawfulness of the NIS under the Lee administration.