North Korea has pledged to strengthen its nuclear weapons programme, after the UN Security Council voted to expand existing sanctions against Pyongyang.

North Korea said on Wednesday it would hold no more talks on the denuclearisation of the Korean peninsula and would boost its military and nuclear capabilities.

"We will take measures to boost and strengthen our defencive military power including nuclear deterrence," its foreign
ministry said in a statement carried by state news agency KCNA.

Hours earlier, the Security Council voted unanimously to condemn North Korea's December rocket launch.