By Jeongeun Lee
SEOUL, March 11 (Reuters) - Opponents of South Korea's ousted leader, Park Geun-hye, demanded on Saturday that she be arrested a day after she was thrown out of office over a corruption scandal involving the country's conglomerates.
Park's critics said they would rally in central Seoul, where they have been gathering every weekend for months, while the former president's conservative supporters also planned protests, raising the risk of confrontation.
The Constitutional Court ruling on Friday to uphold a parliamentary vote to impeach Park infuriated hundreds of her supporters, two of whom were killed as they tried to break through police lines outside the court. A 74-year-old man involved in the protest had a heart attack and died on Saturday, a hospital spokeswoman said.
"We demand the arrest of Park Geun-hye and the resignation of acting president Hwang Kyo-ahn," said Choi In-sook, a spokeswoman for protesters, told Reuters.
Prime Minister Hwang, a Park loyalist, became acting president when parliament voted to impeach her on Dec. 9.
Hwang called for calm on Friday and promised that a snap presidential election, which has to be held within 60 days, would be smooth. The election commission was due to make an announcement on Saturday.
Protesters were setting up equipment in central Seoul early on Saturday and small groups of police were on the streets.
Park is South Korea's first democratically elected leader to be forced from office. He followed months of political paralysis and turmoil over a corruption scandal that also landed the head of the Samsung conglomerate in jail and facing trial.
Park did not appear in court and did not make any comment after the ruling. She spent Friday night in the presidential Blue House residence though would leave at some time, and return to her private Seoul residence, a spokesman said.
FALL FROM GRACE
The court ruling marks a dramatic fall from grace of South Korea's first woman president and daughter of Cold War military dictator Park Chung-hee, both of whose parents were assassinated.
Park, 65, no longer has immunity as president, and could now face criminal charges over bribery, extortion and abuse of power in connection with allegations of conspiring with her friend, Choi Soon-sil.
A liberal candidate, Moon Jae-in, is leading in opinion polls to succeed Park, with 32 percent in one released on Friday.
Relations with China and the United States could dominate the presidential campaign, after South Korea this month began deployment of the U.S. THAAD missile defence system in response to North Korea's stepped up missile and nuclear tests.
Beijing has vigorously protested against the deployment, fearing its radar could see into its missile deployments. China has curbed travel to South Korea and targeted Korean companies operating in the mainland, prompting retaliatory measures from Seoul.
Reform of the country's giant conglomerates, known as "chaebol", will also be an election issue.
Park was accused of soliciting bribes from the head of the Samsung Group, the country's largest conglomerate, for government favours.
Samsung Group leader Jay Y. Lee has been accused of bribery and embezzlement in connection with the scandal and is in detention. His trial began on Thursday.
He and Samsung have denied wrongdoing.
(Additional reporting by Suyeong Lee; Writing by Robert Birsel)