The knife attack on U.S. Ambassador to South Korea Mark Lippert should become a chance to further tighten the South Korea-U.S. alliance, not to imperil it, the prime minister said Friday after his visit to the hospitalized envoy.

The U.S. official is now recovering from surgery in a local hospital after sustaining knife wounds in an attack by a progressive local activist a day earlier.

The 55-year-old activist with a criminal record cut Lippert's face and wrist with a 25-centimeter knife while the ambassador was preparing for a speech at a breakfast event in central Seoul on Thursday.

The prime minister visited Lippert in Severance Hospital in Seoul earlier in the day, accompanied by Vice Foreign Minister Cho Tae-yong.

"I hope (the incident) serves as an opportunity to further strengthen bilateral relations," the prime minister said right after the hospital visit.

"The South Korea-U.S. alliance should not be damaged by this kind of incident, it should be further intensified."

Lee conveyed such hopes for the unswerving Seoul-Washington alliance to Lippert during the meeting and the ambassador agreed with him, the prime minster also added. (Yonhap)