The main opposition Liberty Korea Party on Tuesday called for an independent counsel investigation into suspicions that pro-government supporters with membership of the ruling Democratic Party attempted to rig online public opinions.
Three suspects have been detained for allegedly using a computer program to jack up the number of "like" or "feel the same way" clicks for comments critical of the government on news stories carried by the online portal Naver.
They reportedly told police earlier that they obtained a rigging program and wanted to make it look like conservatives manipulated online opinions as they tried to test the program. The leader is a blogger, surnamed Kim, who goes by the alias "Druking."
The scandal has hit the ruling camp hard, especially in the wake of revelations that Rep. Kim Koung-soo of the ruling Democratic Party, considered one of the closest people to President Moon Jae-in, has known and communicated with Druking since 2016.
The lawmaker has disavowed involvement in the alleged opinion rigging attempts.
"Truth can be revealed only through a special prosecutor investigation," Hong Joon-pyo, leader of the main opposition LKP, said in a Facebook post. "We will stake all National Assembly proceedings to get to the bottom of this case linked to the administration's legitimacy."
Hong said an independent investigation is indispensable as police and the prosecution cannot conduct thorough probes into the case involving top administration officials. He accused police of trying to get Rep. Kim off the hook without sufficient investigation.
Members of the LKP launched an indefinite sit-in protest in front of the main National Assembly building to call for an independent investigation and denounced the way the Moon Jae-in administration runs state affairs, including the embarrassing resignation of Financial Supervisory Service chief Kim Ki-sik.
Kim offered to step down Monday, just two weeks after taking office, following revelations that the former lawmaker used leftover political funds to donate to an organization to which he belongs and that he took overseas trips with money from institutions under the oversight of his parliamentary committee.
Ahn Cheol-soo, a co-founder of the minor opposition Bareunmirae Party, also called for a special investigation.
"We need to appoint a special prosecutor as early as possible because even President Moon Jae-in's involvement is suspected," he told reporters at the National Assembly, pointing out that manipulation of online comments happened during last year's presidential election.