SEOUL, May 17 (Xinhua) -- South Korean prosecutors on Tuesday sought a 17-year prison term against a 56-year-old attacker of Mark Lippert, U.S. ambassador to South Korea, at an appeals court.

The prosecution sought the longer jail term during a hearing at the Seoul High Court as the South Korean man slashed the face and arm of the top U.S. envoy to Seoul with a knife that needed more than 80 stitches.

Kim Ki-Jong, who is serving an imprisonment, was sentenced to 12 years in prison at the lower court for attacking Lippert at a breakfast function in Seoul in March last year.

Later, one and a half years of jail term was added as he assaulted a prison guard and a doctor.

Prosecutors asked the appeals court to convict him for the violation of the national security law, which the lower court acquitted him of.

The prosecution reportedly said that Kim committed the crime in sympathy with the Democratic People's Republic of Korea (DPRK)'s ideology, noting that his crime was premeditated given a fact that he prepared a knife in advance.

Kim's lawyer insisted that he had no intention of homicide. Kim had said it was accidental.