South Korea's major labour group vowed Sunday to hold a massive anti-government protest this week, a day after authorities banned the rally over concerns it could turn violent.
The planned demonstration on Saturday follows a major protest earlier this month -- the largest in more than seven years -- that saw police clash with demonstrators.
Critics say the conservative government of President Park Geun-Hye, daughter of the late heavy-handed ruler Park Chung-Hee, is slipping back into past authoritarian rule.
The Korean Confederation of Trade Unions said the police ban on the planned march was "unconstitutional" and vowed to press ahead with the march.
"Such ban is an outright denial of constitutional rights... and was prevalent only during dictatorship," the umbrella union said in a statement, referring to the 1960-70s era military rule under Park Chung-Hee.
"Our plan to hold the rally remains unchanged," the group added.
Police had on Saturday banned the planned demonstration scheduled for December 5, citing safety concerns.
The protesters are demanding that Seoul scrap its labour reform plan that critics say would make it easier for firms to fire workers. They are also calling for the government to cancel a controversial scheme to impose state-issued history textbooks in schools.
The protests on November 14 -- involving more than 60,000 people -- led to violent clashes with police, who sprayed water cannons and pepper spray at demonstrators.
Police have come under fire for what critics describe as excessive use of force that left dozens injured and one protester in critical condition after he was hit by a water cannon.
President Park condemned the rally as an effort to "deny the rule of law" and urged strong measures against those identified as inciting violence.
Park also called for a ban on wearing masks during demonstrations, drawing parallels between masked protesters and the Islamic State group -- prompting angry reactions from opponents.