The presidential campaign for Lee Jae-myung of the ruling Democratic Party of Korea is embroiled in fresh controversy, this time over accusations of posthumous defamation of two iconic progressive presidents.

The Democratic Party on Saturday uploaded two videos on its official YouTube channel featuring former presidents Roh Moo-hyun and Kim Dae-jung. The videos portrayed the two presidents backing Lee, separately, in the presidential election next month, even though they both died years ago.

In the videos, voiceovers mimicking the two former presidents with the liberal bloc asked voters to cast their ballots for Lee next month citing his background as a member of the working class. Roh and Kim are often touted as the most symbolic figures of progressive political ideology in South Korea.

"I, Roh Moo-hyun, voice support for the righteous candidate Lee who has prevailed in his fights against the privileged class in hopes to bring a world for the people by overcoming poverty and challenges without compromising with injustices," the voiceover said in the video, alongside a file photo of Roh.

"My wife Kwon Yang-sook said she also supported Lee because of his similarity to me. I praise her decision. Even after thinking twice, (my choice) is Lee Jae-myung. The presidency of South Korea is for Lee Jae-myung."

A video featuring a photo of Kim asked viewers to support Lee as he is "a politician who puts words into actions" and that he is a candidate symbolizing "self-consciousness in action."

The two videos immediately sparked anger among voters, with many accusing the Democratic Party of defaming the deceased. Comments flooded the online community website for the ruling party, denouncing the party for taking advantage of the two symbolic figures for political gain.

Many were especially angered to find those videos uploaded on the Democratic Party’s official YouTube channel, and demanded an official apology from Lee and his campaign team.

Some civic groups contended the videos could amount to a defamation of the deceased. Under the Criminal Procedure Act, "in respect to an offense defaming the deceased, any of his/her relatives or descendants may file a criminal complaint."

The Democratic Party deleted the videos from the YouTube channel soon after and told reporters in a statement that the party and its campaign team were not involved in the production. A Lee supporter had made the video in a private capacity and shared it with the party, it said.

Those managing the YouTube channel were given an official warning from Rep. Song Young-gil, head of the Democratic Party, a press official with the presidential election campaign committee for Lee said in the statement.

The statement did not contain an official apology for the matter, and the campaign team did not say whether any such statement or public address in regard to the videos was planned.

The main opposition People Power Party strongly denounced the videos, asking the Democratic Party to come up with preventive measures in response. The party plans to file a complaint with the National Election Commission with regard to the two videos in question.

"This kind of campaign strategy -- mimicking the voice of a former president who died in a tragedy for political use -- is something beyond imagination for our party," People Power Party Chairman Lee Jun-seok said in a Facebook post Sunday.

"The (latest incident) from the Democratic Party did not reflect any official stance of the deceased President Roh Moo-hyun and has caused serious turmoil to voters," he added in another Facebook post posted an hour later.

"We will report this video from the side of candidate Lee Jae-myung to the National Election Commission."

The video featuring Roh also sparked a fuss over a graphic that possibly contains a symbol of the Ilbe Storehouse, a well-known conservative extremist community in South Korea. The community has often been denounced for strongly mocking Roh as well as other liberal politicians.

"The Democratic Party should carefully look at whether there really is a spy among its members," Park Min-young, a presidential election campaign team member for the People Power Party, said in a Facebook post Sunday.

"The fact that the party removed the videos after our feedback could mean that its ability to run checks on itself is completely demolished. I’m only saying this because I am deeply worried."

Lee's campaign team did not respond to the allegation on the use of the Ilbe symbol on Monday.