He was one of an estimated one million South Koreans who marched on Saturday in streets near Seoul's presidential palace, where Park is braced for what is likely to be a bitter and prolonged fight against MPs who may attempt to impeach her as early as next week.

Police said 260,000 people took part in the fifth straight weekend of massive protests against the extremely unpopular president, who prosecutors accuse of assisting criminal activities of a secretive confidante who allegedly manipulated power from the shadows and extorted companies to build an illicit fortune.

Organisers put the turnout at 1.3 million.

"The fatigue is really starting to kick in," said Lee, 53, who, while leading a convoy of farmers, travelled nearly 186 miles from the seaside county of Haenam on his tractor before police on Friday stopped the vehicles near Seoul.

"Pulling Park down isn't going to be easy, but we farmers are good at injecting energy into demonstrations," Lee said.

Thousands of people marched in streets close to the presidential Blue House, areas police usually do not permit, carrying signs and flags. Protesters later turned a darkened boulevard in front of an old palace gate into a sea of light, waving candles and singing and shouting for Park's removal.

The country's largest opposition party said it will seek to propose an impeachment motion for vote as early as Friday and no later than December 9. Some members of Park's conservative party have vowed to support an impeachment attempt, arguing it would serve the party's interests to distance itself from Park ahead of next year's presidential election.

The massive rallies in recent weeks have been mostly peaceful, but there was tension Friday night as police clashed with some of hundreds of anti-Park farmers, who had planned to roll into the capital on tractors and trucks, injuring several people.

Lee and other members of the Korean Peasant League had left two towns in the country's southwest and southeast on November 15 and 16, creating a duo of crawling motorcades that inspired Mad Max comparisons on the internet.

Police blocked the vehicles after a court ruled that the farmers should not be allowed to park or drive them in rally areas.