SEOUL - South Korean President Lee Myung- bak vowed Friday to "immediately and completely punish" the Democratic People's Republic of Korea (DPRK) if it attempts any more provocations.

Calling past provocations by the northern neighbor "premeditated attacks" and not a mistake, Lee, a hard-liner on Pyongyang, said Seoul is confident in its combat readiness and is making military reform efforts.

"As the commander in chief, I will maintain the iron-tight defense of the Republic of Korea," Lee said in a speech marking the 10th anniversary of the naval clash near a disputed western maritime border, which killed six South Korean sailors.

"I will resolutely respond to any provocations and firmly stand up against any attacks," added the conservative leader, who in 2008 effectively ended the policy of inter-Korean appeasement advocated by his liberal predecessors.

The two Koreas, which remain technically at war with each other since the 1950-53 Korean War ended in a truce, have had a few deadly clashes near the western sea border called the Northern Limit Line.

In March 2010, a South Korean warship sunk near the western sea border in what the authorities here said was a torpedo attack by Pyongyang. Forty-six South Korean sailors were killed.

In November that year, the DPRK shelled a South Korean border island and killed four, further deteriorating inter-Korean relations already strained by Lee's hard-line policy towards Pyongyang.

Pyongyang, which refuses to acknowledge the sea border, has repeatedly denied its responsibility for the 2010 sinking and said the shelling was for self-defense.