The South Korean government will not back down on its decision to punish the Democratic People's Republic of Korea (DPRK) for sinking its navy warship despite tough talk of Pyongyang including warnings of a war and severing all remaining ties, Seoul said Wednesday.

Amid heightening tension on the divided Korean peninsula following an international probe that publicly accused the DPRK of having deliberately attacked a South Korean corvette and killed 46 sailors, Pyongyang, denying its responsibility, has issued a series of threats involving an "all-out war" against Seoul's moves to punish it for its alleged aggression.

"North Korea (DPRK) once again took threatening measures that harm inter-Korean ties although it should be taking appropriate steps to apologize for its attack and punish those responsible for it. The (South Korean) government will unwaveringly continue to deal resolutely with the North's threats," unification ministry spokesman Chun Hae-sung told reporters in a briefing.

"We will also go ahead with measures we announced on May 24," he added, referring to a series of punitive measures against Pyongyang, including holding anti-submarine drills with the United States and suspending trade and bilateral exchanges with Seoul's northern wartime rival.

On Tuesday, Pyongyang said it would sever all remaining ties and communication links with Seoul during South Korean President Lee Myung-bak's remaining tenure and expel personnel from a joint consultative office in the border town of Kaesong.

In a statement issued by the Committee for the Peaceful Reunification of Korea, the DPRK also said it will ban South Korean ships and airliners from passing through its waters and air and wage a counterattack against Seoul's anti-Pyongyang propaganda activities that recently resumed after the probe findings pointed a finger at its northern neighbor for the naval tragedy.

The warnings came on the eve of U.S. Secretary of State Hillary Clinton's visit to Seoul in show of support for its Asian ally. She is scheduled to meet with the president and the foreign minister.