'The new born puppy knows no fear of a tiger' - North Korea threatens 'final destruction' of South Korea during debate at UN

North Korea has threatened South Korea with 'final destruction' during a debate on disarmament at the UN, as it said it could take "second and third steps" after a nuclear test last week.

"As the saying goes a new born puppy knows no fear of a tiger. South Korea's erratic behaviour would only herald its final destruction," North Korean diplomat Jon Yong Ryong told the meeting.

The threat came as Moscow opposed new economic sanctions on North Korea but said it would be ready to back measures to limit nuclear proliferation, a Russian official said on Tuesday.

Pyongyang was widely condemned last week after its third nuclear test since 2006, defying United Nations resolutions and putting the country closer to a workable long-range nuclear missile

Without specifically referring to the nuclear test, Jon said North Korea had recently taken a "resolute step for self-defence", which he described as "strong counter-actions to a foreign aggressor".