North Korea has threatened to blow up all of Seoul in response to anti-North Korea rallies held in the South Korean capital last Sunday.

The North’s state-run Korean Central News Agency said a spokesman for the Supreme Command of the Korean People's Army issued the threat on Wednesday.

The news agency quoted the spokesman as saying the Lee Myung-bak government had debased the dignity of North Korea's leadership last Sunday as the North marked the 100th birthday of its founder Kim Il-sung.

The spokesman claimed Lee's government masterminded the anti-North Korea rallies held in central Seoul last week. The spokesman added the North will take special measures to blow up all of Seoul.

On Sunday, members of a conservative civic group held a rally in Gwanghwamun Square and denounced the North's launch of a long-range rocket. Earlier on Friday last week, a group of college students condemned the North's third-generation power succession in a rally at the same site.