Police said Monday they will sternly deal with violent protesters, referring to a massive rally planned for this coming weekend, setting the stage for another clash.

The remarks came after an association of liberal civic groups vowed to go ahead with the rally in central Seoul on Dec. 5, despite a prohibition order from the police.

Police said they will use colored sprays to filter out violent demonstrators, making it easier to arrest them on the spot and deter the protest from becoming violent.

"(If protesters) intrude across the police line and advance toward banned areas under the name of a peaceful rally, it is not a law-abiding demonstration," Goo Eun-soo, the chief of the Seoul Metropolitan Police Agency, said.

Earlier this month, tens of thousands of demonstrators took to the streets in downtown Seoul to protest the government's decision to adopt state history textbooks and reform the labor market. The rally later turned violent as some protesters brandished metal pipes and police fired water cannons at them.

A 69-year-old farmer suffered a brain hemorrhage after being knocked down by a police water cannon.

President Park Geun-hye has vowed not to tolerate "illegal" demonstrations and instructed officials to come up with strong measures to root out violent protests. (Yonhap)