The government of the Democratic People's Republic of Korea (DPRK) will"vanish from the earth" if it wages a nuclear attack on South Korea, the South Korean Defense Ministry said Friday.

"I am telling you this as a member of the human race: If North Korea (DPRK) attacks South Korea with nuclear weapons, the Kim Jong Un regime will vanish from the earth by the will of the humanity,"ministry spokesman Kim Min-seok told reporters.

The remark came shortly after the DPRK said it would sever a military hotline with South Korea and nullify non-aggression agreements between the two countries, a response to newly expanded sanctions approved by the UN.

The toughened sanctions dictate UN member states inspect DPRK ship and air cargo suspected of carrying banned materials and tighten scrutiny of DPRK officials and institutions engaged in illicit activities.

The unanimous decision by the 15-member UN body came after the DPRK's underground nuclear test last month, a follow-up to the controversial December rocket launch largely seen as a disguised missile test.

South Korea, which expressed support for the fresh sanctions, has stepped up its border surveillance and is ready to"immediately retaliate"if attacked, according to the spokesman.

Defense minister-nominee Kim Byung-kwan, who is going through a parliamentary confirmation hearing, vowed to "substantially strengthen" deterrence against security threats.

The South Korean military, which recently announced its plans to develop long-range missiles and a missile defense system of its own, has also said it will "strike back" at the DPRK and its" command leadership" if attacked.