North Korea's third nuclear test and threats of military action are "completely unacceptable," UN Secretary-General Ban Ki-moon said in remarks published on Saturday, urging Pyongyang to feed its people and seek peace with South Korea.
North Korea threatened the US on Thursday with a pre-emptive nuclear strike and has scrapped the armistice with Washington that ended hostilities in the 1950-53 Korean War.
That followed its third nuclear test on February 12, in defiance of UN resolutions, drawing further UN Security Council sanctions against the reclusive East Asian state.
Asked by Austria's Profil magazine about North Korea's nuclear test, military exercises and threats, Ban, a former South Korean foreign minister, said, "I find this completely unacceptable and it is also a challenge for the international community."
He said in an interview with Profil that he had urged the North Korean leadership to focus on the welfare of its own people in the face of serious economic problems.
North Korea formally rejected a UN Security Council resolution on Saturday demanding an end to its nuclear arms program and China called for calm, saying sanctions were not the "fundamental" way to resolve tensions.