The South Korean government on Tuesday petitioned the constitutional court to disband a far-left political party branded as pro-North Korean.
The cabinet decided that the objectives of the Unified Progressive Party (UPP) ran counter to the "basic democratic order of the constitution", Justice Minister Hwang Kyo-Ahn told reporters.
The cabinet vote came months after a number of UPP members including MP Lee Seok-Ki were arrested on charges of plotting an armed revolt in support of North Korea.
Hwang said Lee headed a group that formed the core of the UPP and followed North Korea's strategy to "revolutionise the South".
The main opposition Democratic Party, which had approved Lee's arrest, described the unprecedented move to disband the UPP as "very regrettable".
"We hope for a responsible and wise decision by Constitutional Court justices, based on historical awareness," said party spokesman Kim Kwan-Young.
The cabinet petition was reportedly sanctioned online by President Park Geun-hye, who is on an official visit to Europe.
The UPP reacted by accusing Park's government of "trampling" over democratic principles.
The party also suggested it was an effort to distract attention from a widening probe into allegations that the domestic spy agency interfered in last December's presidential election.
"This is not only a suppression against the UPP but vandalism against democracy ... the demise of this regime has become inevitable," the UPP said in a statement.
The UPP had fielded a candidate, Lee Jung-Hee, in last year's presidential race.
Lee made a big splash in the first TV election debate with a sustained, personal attack on a visibly rattled Park, describing her as arrogant, self-righteous and a "dictatorial queen".
At the time, Lee said the best political reform for South Korea would be the disappearance of Park's ruling New Frontier Party.