Some of the protesters marched to a point just 100 meters from the Constitutional Court to pressure it to quickly review the impeachment case.

After the legislature impeached Park, she was suspended from all powers, and Prime Minister Hwang Kyo-ahn took over as acting president. The Constitutional Court will determine whether to unseat Park or reinstate her after a legal review that could last up to six months.

A day earlier, Park's attorneys dismissed all impeachment charges, urging the court to reject the parliamentary decision to impeach Park.

The participants in the rally demanded that Park bow out and face a probe over the suspicions that she allowed Choi to meddle in important state affairs, including high-level government appointments, and profit by exploiting her ties to the president.

"Park must step down right now, and her resignation itself is not enough. She must be held accountable for any wrongdoings she allegedly carried out," Shin Sang-jun, a 75-year-old citizen from Yangju, northeast of Seoul, told Yonhap News Agency.

Kim Dae-sol, a 17-year-old high-school student, said that the president must listen attentively to public voices demanding her resignation.

"In a free democracy, citizens entrust the president with power. That is what I learned from my school, and the president does not seem to understand this," he said.

Some others called for Acting President Hwang to immediately step down, arguing that Hwang, appointed by the president, is maintaining the "Park regime."

Supporters of the president and dozens of conservative civic groups also staged a separate rally, saying that the impeachment of Park must be nullified. Some of them said that anti-Park protesters are part of leftist political forces worsening the national confusion sparked by the political scandal.

"There is no clear evidence yet that verifies Park's legal violations and there are only suspicions," Choi Jae-woo, a 68-year-old citizen in Seoul, said.

"Even if she did anything wrong, the process of holding her responsible should come only after Park completes her term. The demand for her immediate resignation is only exacerbating the national confusion," he said.

Saturday's rally put the presidential office Cheong Wa Dae on edge.

"We gravely hear the people's voices, and we are closely watching the situation related to the weekend rally," a presidential official told Yonhap News Agency over the phone, declining to be named.

Amid concerns about the possible clashes among anti-Park protesters and Park's supporters, police dispatched some 18,200 police officers to areas in downtown Seoul.

On Saturday, rallies were held in many cities across the country, including Ulsan, Busan and Gwangju.

Potential presidential contenders from the opposition parties joined the rallies, calling for Park's early departure from office.

Rep. Moon Jae-in, former leader of the main opposition Democratic Party, joined a rally in Ulsan. He stressed that the candlelight rally is the "crucial opportunity to break away from the old era and old system."

Protesters have been taking to the streets in Seoul and other cities across the country for the past two months. Rallies have been held peacefully with no serious clashes with riot police.

There were some of the largest demonstrations held in the country's history, with the rally held right before the parliament's impeachment vote gathering some 1.7 million protesters in Seoul alone, according to organizers. (Yonhap)