Seoul - Tens of thousands of people took to the streets of central Seoul Saturday in a massive protest against the conservative government's drive for labour reform and state-issued history textbooks.
Police sprayed water on the crowd, estimated to number about 50,000, as some protesters attempted to push through barricades at the rally outside City Hall in central Seoul.
Ahead of the rally, labour unionists scuffled with scores of plainclothes policemen to prevent the arrest of the head of the militant Korean Confederation of Trade Unions (KCTU), who showed up for a press conference near the protest site.
Labour activists successfully blocked police from arresting KCTU President Han Sang-Kyun, who has been sought for leading outlawed labour strikes last year and May Day protests this year.
"Down with (President) Park Geun-Hye", the unionists chanted following the scuffles, calling her conservative government "fascist", an AFP journalist on the scene said.
Authorities said they had mobilised 20,000 riot police for fear that the protest might turn violent.
Organisers of the protest said there would be a march toward the presidential Blue House, a move which is likely to spark a clash with police.
Participants, many of whom were bused in from across the country, chanted slogans demanding the withdrawal of a government labour policy which KCTU says benefits businesses by keeping wages low and making it easier for companies to fire activists.
They also condemned the opening of protected markets for some agricultural goods and a plan to impose government-issued textbooks on schools starting in 2017.
The textbooks have become a bitter ideological battleground between left and right in South Korea, with critics accusing Park's administration of seeking to deliberately manipulate and distort the narrative of how the South Korean state was created.
Conservative critics argue that currently the authors are too left-wing, but liberal opponents accuse the government of reverting to a policy used by past authoritarian regimes in South Korea including that of late president Park Chung-Hee, father of the current president.
Saturday's rally was the largest South Korea has seen since 2008 when the country was hit by waves of protest against the import of US beef.