North Korea has threatened strong retaliation against South Korea for allegedly drafting a contingency plan to respond to an emergency in the North.

The North's National Defense Commission said in a statement Friday that the South's contingency plan is a plot to overthrow the North's Socialist system.

The statement said North Korea will launch a sacred war on the South to destroy its key facilities including the presidential office Cheong Wa Dae to punish it for the alleged plot.

The statement also said if South Korea does not apologize for an alleged anti-North Korean action, it will be excluded from all talks and negotiations aimed at guaranteeing peace and security on the Korean Peninsula.