SEOUL (AFP) - South Korean authorities have warned they will take a hard line against a large-scale anti-government protest planned for central Seoul on Saturday (Nov 14).

Speaking on television, the country's justice minister, flanked by the labour minister and three vice-ministers of agriculture, education and administration, said any sign of violence or illegal gatherings would be firmly dealt with.

"The government hereby makes it clear that any illegal mass action or violence will be strongly dealt with," Minister Kim Hyun Woong said.

Police warned protesters to remain in a designated area, not to clash with officers and said demonstrators were not permitted to march towards the presidential Blue House.

Organisers hope as many as 100,000 people will turn out for the "People's General Uprising" - a protest rally bringing together workers, farmers, teachers and social activists, among others.

The rally will focus on a series of issues, including the government's planned labour reforms, the opening of protected markets for some agricultural goods, and the imposition of state-issued history textbooks in schools.

State school teachers were warned on Friday they would be punished if they took part in the rally in violation of clauses banning them from engaging in political activism.

"We will deal sternly with any activities that run counter to teachers' duties and obligations," said Vice-Education Minister Lee Young.

The planned march follows a protest involving thousands of workers earlier this year who gathered in the capital to fight proposed labour reforms at a May Day rally.

The protesters clashed with riot police who fired water cannon laced with a chemical irritant and erected barricades to block the demonstrators from marching towards the office of President Park Geun Hye.