South Korea's main opposition party leader Lee Jae-myung was stabbed in the neck just now during a visit Busan. He was bloodied but fortunately in a conscious-state at the hospital, party officials confirmed.

The politician was touring the construction site of the Gadeokdo New Airport and talking to reporters when he was attacked, leaving him with a 1 cm laceration on the left side of his neck, Democratic Party spokesperson said.

He suffered suspected damage to his jugular vein and will quickly undergo a surgery at the Seoul National University Hospital, the spokesperson noted, describing the attempt on Lee's life an act of terrorism and a serious threat to democracy.

The assailant, who was arrested at the scene, is a man in his sixties. He approached Lee for an autograph before carrying out the attack with an 18 cm long knife purchased online, said the police.

Footage of the attack was captured on live television at the press conference, and showed the assailant at the front of the crowd suddenly lunging at Lee and striking him in the neck, sending Lee collapsing backwards.

The attacker was then wrestled to the ground and restrained by several people. Photos showed Lee lying on the floor with his eyes shut and a handkerchief pressed against his neck.