Saturday’s anti-President Park Geun-hye rally in Seoul is likely to be the largest candlelight vigil ever to be held in South Korean history, police said Thursday, exceeding that of the 2008 anti-US beef uproar. 

Organizers -- a union of some 1,500 civic organizations and labor groups -- expect at least 500,000 participants, while police anticipate 160,000.

Even by police projections, the upcoming rally would double the size of the anti-US beef protest, which police put at 80,000. At the time, organizers reported 700,000 participants. 

Scheduled to begin at 4 p.m. at Seoul Square in front of Seoul City Hall, the event will be the third massive demonstration of public anger against President Park since the scandal involving her confidante Choi Soon-sil erupted. 

Unlike the previous two, the upcoming rally is expected to be joined by nearly all forces that oppose the scandal-hit conservative leader, from unionized labor, civic groups, political parties and their bigwig politicians to unaffiliated citizens.

Labor groups had planned the demonstration long before the scandal over labor-related issues. The nation’s three main opposition parties -- including the main opposition Democratic Party of Korea -- decided to join Wednesday.

Over 20,000 police will be deployed to control the joint rally, according to authorities. It added it will avoid actions that may provoke violent clashes with the demonstrators.

Street protestor Baek Nam-gi died in September, several months after he was knocked down by a police water cannon blast at an anti-government rally last year in November. He remained hospitalized in a coma following the blast.

The Korean Confederation of Trade Unions originally planned to march toward Cheong Wa Dae, the presidential office, at 5 p.m., but police decided to disallow the movement.

Authorities plan to block protestors from moving past Gwanghwamun Square, some 100 meters from the Seoul Square, toward the direction of Cheong Wa Dae.

Another group reported plans to march toward the presidential office, but were also denied by police.

Seoul, whose mayor plans to join the rally, is gearing up for the massive gathering, such as by checking 50 roadside ventilation openings for safety. It also plans to deploy 15 ambulance squads and 70 paramedics and increase the number of safety guards inside subway stations on the day.

The protest comes amid continuing public anger over the scandal involving President Park’s longtime confidante Choi. In the previous rally Saturday, some 200,000 people flocked to Gwanghwamun Square to fill the streets in candlelight.

Park is suspected of allowing Choi, a civilian, to meddle in state affairs. Choi allegedly took advantage of her relationship and interfered in presidential speeches and assignments, as well as siphoning funds from businesses.

Before the 2008 US beef fiasco, South Korea saw a massive candlelight vigil in 2004 against the parliament’s passage of a motion to impeach President Roh Moo-hyun. An official police count of protesters at the time was put at 130,000.

By Jo He-rim (herim@heraldcorp.com)