Watch | South Korea opposition chief Lee Jae-myung stabbed by autograph-seeker

Seoul: South Korea's opposition Democratic Party leader Lee Jae-myung was stabbed in the neck during a visit to the southern city of Busan on Tuesday and was airlifted to a university hospital for treatment, party and fire officials said.

Lee, who narrowly lost the 2022 presidential election, was conscious and being flown to Seoul National University in the capital after receiving emergency treatment at the Pusan National University Hospital, party spokesman Kwon Chil-seung said.

The transfer to Seoul was possible after medical staff determined his condition was not life-threatening based on emergency treatment and a CT scan, a Pusan National University Hospital official told Reuters.

Kwon, speaking outside the hospital soon after Lee was airlifted by helicopter, said Pusan National University Hospital medical staff suspected damage to a jugular vein that carries blood from the head to the heart.

"There is concern that there could be large haemorrhage or additional haemorrhage, according to medical staff," Kwon said.

The attack by the assailant, seen in video footage and photographs, unfolded quickly while Lee was touring the site of a proposed airport in Busan.

The man - who appeared to be in his 50s or 60s and wearing a paper crown with Lee's name on it - approached and asked for an autograph as Lee spoke among a throng of supporters and reporters, then lunged forward and attacked him, video footage showed.

Television footage and a video clip on the social media platform X showed the man lunging with his arm stretched out and stabbing Lee in the neck, the force of the attack pushing Lee back into the crowd behind him.

Lee grimaced and collapsed to the ground.

News photographs showed Lee lying on the ground with his eyes closed and bleeding, and people pressing a handkerchief against his neck.

Jin Jeong-hwa, a Lee supporter who was at the scene livestreaming the event, told Reuters there were more than two dozen police officers present.

The assailant was quickly subdued by men including police officers, the footage showed.

He was refusing to answer police questions about his motives, daily Busan Ilbo reported.

President condemns attack

President Yoon Suk Yeol condemned the attack and instructed best care be given, his office said.

"This type of violence must never be tolerated under any circumstances," his office quoted Yoon as saying.

A former governor of Gyeonggi province, Lee narrowly lost to conservative Yoon, a former chief prosecutor, in the 2022 presidential election. He has led the main opposition party since August 2022.

Lee is currently on trial for alleged bribery stemming from a development project when he was mayor of Seongnam near Seoul. He has denied any wrongdoing.

South Korea's next parliamentary elections are slated for April.

South Korea has a history of political violence although it has strict restrictions on gun possession. There is police presence at major events but political leaders are not normally under close security protection.

Lee's predecessor, Song Young-gil, was attacked in 2022 at a public event by an assailant who swung a blunt object against his head, causing a laceration.

Then conservative opposition party leader Park Geun-hye, who later served as president, was stabbed at an event in 2006 and suffered a gash on her faced that required surgery.

Her father, Park Chung-hee, who was president for 16 years after taking power in a military coup, was shot and killed by his disgruntled spy chief in 1979 at a drunken private dinner.

In 2015, then US ambassador to South Korea, Mark Lippert, was attacked by an assailant while attending a public event, suffering a large gash on his face.