A record number of protesters are set to gather in central Seoul on Saturday, as parliament takes steps to impeach President Park Geun-hye after state prosecutors accused her of being an accomplice in the influence-peddling and corruption scandal linked to her confidante.

With the opposition parties planning to put the impeachment motion up for a vote in early December, local police said around

1,500 liberal and progressive civic groups have organized a massive rally around Gwanghwamun Square calling for Park to step down.

Organizers estimate upwards of 1.5 million will join the rally, higher than some 600,000 participants observed last week. 

Two weeks ago, over a million protesters gathered in the capital city, the highest number in nearly three decades. Similar protests will be staged at major cities around the country.

While previous protests ended peacefully, police said they will deploy some 25,000 officers to guard against any eventualities.

The rally marks the fifth of its kind after the outbreak of the scandal in which Choi Soon-sil, who has been Park's friend for more than 40 years, is suspected of exerting influence on state affairs despite holding no official position in the incumbent administration. 

A rising number of South Koreans have been expressing anger over allegations that Choi exerted influence in the business, cultural and sports areas.

Reflecting the sentiment, Gallup Korea said Park's approval rating fell to another record-low level of 4 percent this week, down 1 percentage point from a week earlier.

Local observers said more participants will join the latest protest after prosecutors claimed Park was complicit in the scandal, which led opposition parties to officially seek the president's impeachment. The main opposition Democratic Party said it will put the motion up for vote no later than Dec. 9.

Park's attorney rejected the prosecution's investigation results, claiming prosecutors lacked "fairness and credibility" and even hinted at political bias. 

The presidential office blasted the allegations raised by prosecutors as being based on wishful thinking with no basis in fact and said Park will not accept questioning.

As the successful passage of the motion calls for support from at least 200 lawmakers, the opposition bloc needs to persuade 28 members from the Saenuri party to support it. Pundits said the figure seems plausible, considering some 40 lawmakers of the ruling party are anticipated to join the move.

Once the motion is passed, the Constitutional Court will review the case. It took 63 days for the court to dismiss the impeachment motion against late former President Roh Moo-hyun.

Next week, the parliament will kick off the parliamentary investigation of the scandal separately from the prosecutors'

probe, starting by questioning the cultural and justice ministries.

It will also investigate the presidential office and other organizations later in December.

The parliament's special committee carrying out the parliamentary investigation said it has decided to call in major business leaders, including Samsung Group's heir-apparent Lee Jae-yong, along with the heads of LG Group, Hyundai Motor Group and SK Group in December.

Local conglomerates were reportedly requested to chip in for the establishment of the Mir Foundation and the K-Sports Foundation, with allegations indicating that Choi tried to siphon off money from these entities. Samsung is also suspected of providing favors to Choi's daughter. (Yonhap)