South Korea's Constitutional Court has ruled to disband a minority left-wing party and strip its five members of parliament of their seats after accusing them of pro-North Korea activities that it said violated the basic principles of free democracy.
"First, we order the dissolution of the Unified Progressive Party (UPP). Second, the party's lawmakers will lose their seats in the National Assembly," the chief judge, Park Han-chul, said on Friday.
"There was an urgent need to remove threats posed by the party against the basic principles of democracy," the judge added.
South Korea's government welcomed the court's ruling.
"The constitutional court's ruling clearly confirms that the Unified Progressive Party (UPP) tried to overthrow our liberal democracy by using violence and realise the North Korean-style of socialism," Prime Minister Chung Hong-won said.
"The government will not tolerate any attempts or action to repudiate the legitimacy of the Republic of Korea or damage or challenge our liberal democracy. We will firmly respond against them," Chung added.
The case against the UPP brought by the government of President Park Geun-hye has been played out amid a bitter struggle between conservatives and liberals in a country sharply divided over ideology and North Korea.
The ruling to disband a political party required the votes of six of the nine judges.
UPP leader Lee Jung-hee condemned the ruling and called the country a "dictatorial regime".
"I failed to carry out my last duty to protect democracy. The 15 years of progressive politics and the progressive party are taken down by the dictatorial regime," said Lee after the ruling.
The party, which says it speaks for the working class and progressive members of society, has led a stormy existence since its founding in 2011, including the conviction of one member of parliament earlier this year on charges of treason.
Amnesty International expressed concern at what it said was the use of national security to repress political opposition.
Its statement said the disbanding of the UPP raises serious questions as to the authorities' commitment to freedom of expression and association.