NORTH KOREA vowed yesterday to bolster its nuclear firepower in response to sanctions passed by the UN security council on Saturday.

In a statement carried by state news agency KCNA, the government said the sanctions were a “violent infringement of its sovereignty” caused by a “heinous US plot to isolate and stifle” North Korea.

The regime insisted that the UN sanctions would not force it to negotiate over its nuclear weapons programme or to stop its push to strengthen its atomic capability. Pyongyang vowed to take “action of justice” but did not elaborate.