The National Intelligence Service is seeking another charge against far-left lawmaker Lee Seok-ki of taking sides with an enemy state against the government.

On Sunday, the NIS questioned Lee for the third day on his charges including plotting and instigating a rebellion, and praising an anti-state entity, but he refused to speak, investigators said. He was detained Thursday after parliamentary approval.

For the fresh charge stipulated under Article 93 of the Constitution, which can carry a maximum penalty of death, the NIS is trying to find what connections he has to North Korea and looking for past remarks or activities in support of the communist state.

Investigators also have to review whether North Korea can be classified as an enemy state. In a 1983 ruling, the Supreme Court defined the North as an anti-state organization rather than a legitimate state.

But the ruling said that in an espionage case, the North should be treated as a “quasi-state.” Legal experts say that in broader legal terms, the North can be described as a state.

Lee and three of his party colleagues have been detained on charges of conspiring to revolt. They have so far denied all allegations, claiming that the “politically-driven” spy agency trumped up the charges amid their calls for a thorough revamp of the NIS.

As part of the high-profile probe, the NIS has indentified some 80 of the 130 people who attended a clandestine May meeting of the “revolutionary organization” ― an underground group where Lee and other leftists allegedly discussed the revolt.

It plans to summon them soon to confirm the charges. Among them are UPP Reps. Kim Jae-yeon and Kim Mi-hee.

Denying all charges against her, Rep. Kim Jae-yeon said she could establish her innocence should she be questioned. All those in question argue that the revolutionary group does not exist.

As media churn out reports of the alleged anti-state conspiracy, the North berated the South’s investigative authorities for scrambling to connect the case to the North and dampening the reconciliatory mood.

“(The attempt at connecting the case to the North) is a challenge to the public demand for reunification and an unbearable affront to our sincerity and efforts (to improve inter-Korean ties),” said the Rodong Sinmun, the daily of the North’s ruling Workers’ Party, said in an article Sunday.

On Friday, the North’s Committee for the Peaceful Reunification of Korea said, “Should the case affect the inter-Korean ties, the South Korean authorities would face the entire responsibility for that.”

As calls for the dissolution of the UPP, the Justice Ministry has formed a special taskforce to determine whether to ask the Constitutional Court to rule on the fate of the disgraced party.

“The ministry plans to devise measures to deal with the issues related to political parties and organizations that threaten the basic order of free democracy,” a ministry official told media on condition of anonymity.

A series of civic groups staged rallies to criticize the UPP and call for a thorough investigation into the case. Among them was Korea University’s student council.

“Should Lee’s charges be confirmed, this would be an act of shaking the country’s foundation. Lee should cooperate with the investigation to ascertain the facts,” the council said during a press conference in Seoul on Saturday.

By Song Sang-ho (sshluck@heraldcorp.com)