North Korea on Monday vowed to "steadily update and strengthen" its nuclear arsenal, rejecting a joint statement by the Group of Seven Foreign Ministers calling for Pyongyang to give up its nuclear ambitions.

North Korea's Foreign Ministry said that its "nuclear armed forces will exist forever as a powerful means of justice," according to state media.

North Korea said on Monday it will steadily upgrade and bolster its nuclear armed forces and blamed the foreign ministers of G7 states for infringing on its sovereign rights by demanding the end of its nuclear weapons programme,

North Korea on Monday denounced the top diplomats of the Group of Seven (G7) countries' joint call for Pyongyang to abandon its nuclear weapons, threatening to strengthen its nuclear forces both in "quality and quantity.