The US ambassador to South Korea is in a stable condition after he was slashed on the face and wrist by a man wielding a 10in knife who called for the rival Koreas to be unified, officials have said.

Media images showed a stunned-looking Mark Lippert staring at his blood-covered left hand and holding his right hand over a cut on the right side of his face, his pink tie splattered with blood.

The US state department condemned the attack, which happened at a performing arts centre in Seoul as the ambassador was preparing for a lecture about prospects for peace on the divided Korean Peninsula. Mr Lippert's injuries are not thought to be life-threatening.

The US embassy said Mr Lippert is in stable condition after surgery at a Seoul hospital.

YTN TV reported that the suspect - identified by police as 55-year-old Kim Ki-jong - screamed during the attack: "South and North Korea should be reunified."

The comments appear to reflect a bitter, lingering political division in South Korean society over the 1950-53 Korean War's legacy and the continuing split of the Korean Peninsula along the world's most heavily armed border.

One witness, Ahn Yang-ok, the head of the Korean Federation of Teachers' Associations, told YTN that Mr Lippert had just been seated for breakfast ahead of the lecture organised by the Korean Council for Reconciliation and Cooperation when a man ran toward the ambassador from a nearby table.

A separate, unidentified witness said that as Mr Lippert stood up for a handshake, the suspect wrestled the ambassador to the ground and slashed him with a knife.

Yonhap TV showed men in suits and ties piled on top of the attacker, who was dressed in a modern version of the traditional Korean hanbok costume, with Mr Lippert later being rushed to a police car with a blood-soaked handkerchief pressed to his cheek. The suspect also shouted anti-war slogans after he was detained, police said.

A police official said the suspect threw a piece of concrete at the Japanese ambassador in Seoul in 2010. South Korean media reported that Kim Ki-jong was later sentenced to a three-year suspended prison term over the attack.

Kim, who was protesting over Japan's claim to small disputed islands that are occupied by South Korea, missed the ambassador with the concrete and hit his secretary instead, the reports said.

Kim also reportedly tried to set himself on fire while protesting in front of the presidential Blue House in October 2007. He was demanding a government investigation into an alleged 1988 rape in Kim's office, according to news reports.

South Korea's foreign ministry released a statement condemning the attack and vowing a thorough investigation and strengthened protection of embassies.

The suspect's reported comments on Korean reunification point to continuing political turmoil linked to the Korean War.

The US, which backed South Korea during the war against China-backed Pyongyang, still stations 28,500 troops in South Korea as a deterrent against North Korea, and some South Koreans see the US presence as a barrier toward a reunified Korea - a view North Korea's propaganda machine regularly pushes in state media.

Anti-US protesters in Seoul have recently demonstrated against annual US-South Korean military exercises that North Korea says are preparation for an invasion. Seoul and Washington say the drills, which will run until the end of April, are defensive and routine.

North Korea reacts with fury to the drills, which the impoverished country is forced to respond to with drills and weapons tests of its own.

In 2013 it threatened nuclear strikes on Washington and Seoul, and on the first day of this year's drills on Monday, it test-fired short range missiles in a demonstration of anger.

Mr Lippert, 42, became ambassador in October of last year and has been a regular presence on social media and in speeches and presentations during his time in Seoul.

His wife gave birth here and the couple gave their son a Korean middle name. Mr Lippert was formerly the US assistant secretary of defence for Asian Affairs and a foreign policy aide to president Barack Obama when Mr Obama was a US senator.

Mr Obama called Lippert after the attack to express his prayers for a speedy recovery, the White House said.

State department spokeswoman Marie Harf said: "We strongly condemn this act of violence."