South Korean President Lee Myung-bak said on Friday that government countermeasures against Pyongyang's torpedo attack should be made prudently and without mistake, Yonhap reported.

Lee said that the Democratic People's Republic of Korea (DPRK)'s torpedo attack on the South Korean warship Cheonan is tantamount to "a military provocation" and a violation of the armistice agreement.

The incident is "serious and significant," Lee told an emergency meeting of his National Security Council (NSC) earlier Friday to discuss follow-up measures to deal with the Cheonan incident.

To deal with the incident, the government should not only take account of military, international aspects and current inter-Korean ties and its future, but also analyze its impacts on the South Korea's society and its economic situation, Lee said.

South Korea on Thursday announced the outcome of investigations over the Cheonan incident made by a multinational team, which said the warship that sank near a tense maritime border with the DPRK in March was torpedoed by a DPRK submarine.

The DPRK on Thursday immediately rejected the claim, saying it will dispatch inspectors to South Korea to verify Seoul's claim.