Hundreds of thousands of South Koreans marched in Seoul to surround embattled President Park Geun-hye's office, forming a "human chain" to demand her resignation on Saturday.
As of 4 p.m. (local time), organisers estimated over 200,000 people gathered around the Gwanghwamun Square, just over a km away from the Blue House, Xinhua news agency reported.
The demonstrators marched up to 200 metres from the presidential palace, Blue House.
Park's office was encircled by a chain of protesters in three sides along the wall of police buses that were parked to prevent an attempt to enter inside the presidential office.
The association to make the Park Geun-hye administration resign, composed of about 1,500 civic groups, held a preliminary event for three hours before the march to the Blue House.
The advocacy groups' association forecast that around 1.5 million people would take to the streets in the Seoul protest alone.
It would become the country's largest ever demonstration in downtown Seoul.
At the third Saturday rally on November 12, around 1.3 million people marched in the capital city, surpassing the June 1987 demonstration that drew about a million protesters.
This Saturday, about 500,000 people are expected to turn out in major cities across the country, according to the estimate by organisers.
Public anger is escalating as Park has dismissed growing calls for her voluntary resignation. Instead, the presidential office encouraged politicians to push forward impeachment.
Impeaching Park could be a political challenge for opposition parties as the process can take months and cause division.
Opposition parties said it would put the bill to vote as early as next Friday.
Saturday's protest may beat the organisers' expectation given that the previous four rallies ended in an orderly and peaceful manner.
Police reportedly mobilised 25,000 officers in Seoul to brace for a possibility that the rallies turn violent and to prevent some protesters from marching inside the Blue House.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)