Lee Jae-myung, the leader of South Korea's main opposition party, was stabbed in the neck on Tuesday morning by a man who asked him for an autograph, police said.
Mr. Lee, 59, the leader of the Liberal Democratic Party, was making his way through a crowd in the port city of Busan when he was attacked, according to police and live television coverage of the incident. He had just answered journalists' questions after touring the site of a planned airport.
Police in Busan said the attacker, a 66-year-old man, had been arrested and was being investigated for possible attempted murder charges. However, they gave no details about Mr Lee's condition or the motives of the attacker, who was said to have used a knife with a five-inch blade.
According to news reports and photos from the scene, Mr. Lee was bleeding from the neck before he was taken away in an ambulance. He was taken to a hospital in Busan and then flown by helicopter to Seoul for treatment at Seoul National University Hospital.
Mr. Lee is conscious and recovering from a two-hour operation to remove blood clots and patch a damaged carotid artery in his neck, Kwon Chilseung, a spokesman for his party, said during a news conference at the hospital on Tuesday evening.
“It was close because it was not an artery but a vein” that was punctured, said Jung Chungrae, a senior Democratic Party member, citing doctors.
Footage of the attack showed the attacker walking towards Mr Lee through a group of television cameramen, apparently posing as one of his supporters; He was wearing what looked like a paper or plastic crown with the words “I am Lee Jae-myung.” Supporters and police officers subdued the man after the stabbing and took him to a police car.
“The man walked up to Mr. Lee and asked him for an autograph in a loud voice,” Son Je-han, a senior investigator with Busan police, told reporters at a news conference.
Mr Lee narrowly lost to conservative Yoon Suk Yeol in South Korea's last presidential election in 2022. Since then he has been the subject of a series of investigations by the public prosecutor's office into corruption and other crimes.
He denied all allegations against him and went on a three-week hunger strike in protest last year, accusing Mr Yoon of using the criminal justice system to intimidate his political opponents. A court barred prosecutors from arresting Mr. Lee, but he faces a series of trials.
Mr. Yoon expressed “deep concern” about Mr. Lee's safety on Tuesday and directed his government to conduct a rapid investigation into the attack and provide support for his medical treatment, the president's office said in a statement.
“The President emphasized that this form of violence should not be tolerated in our society under any circumstances,” the statement said.
South Korean opinion is sharply divided over Mr. Lee, who is widely expected to run for president again in 2027. His progressive supporters consider him to be a clear champion of the poor and social minorities, while his conservative critics describe him as a corrupt populist.
The country's politics have become increasingly polarized in recent years, and with a general election approaching in April, rancor between Mr. Yoon and Mr. Lee's supporters is growing.
However, physical attacks on politicians were rare. In 2006, conservative politician Park Geun-hye, then opposition leader, was slashed in the face with a box cutter by a man who had harshly criticized her. Ms. Park won the 2012 presidential election.
In 2015, a self-described nationalist who had expressed anti-American sentiments cut the face of Mark W. Lippert, then the U.S. ambassador to South Korea, with a kitchen knife.
The Democratic Party views the stabbing of Mr. Lee as an “act of terrorism” and an “attack against democracy,” party spokesman Kwon said.
Yoon Hee-keun, the head of South Korea's National Police, ordered increased security measures for politicians and other prominent officials.