Nukes defence against US blackmail: N Korea

North Korea yesterday sought to justify its weapons programme as a defence against US nuclear "blackmail" as world powers debated ways to punish Pyongyang for its fifth and most powerful atomic test.

The United States, Britain and France pushed the United Nations Security Council on Friday to impose new sanctions on North Korea over its fifth and biggest nuclear test as the 15-member council condemned the move by Pyongyang.

The Security Council agreed to start work on just that -- even though five sets of UN sanctions since the first nuclear test a decade ago have failed to halt the North's drive for what it insists are defensive weapons.

The yield from Friday's test, which sparked international shockwaves, was estimated at 10 kilotons -- almost twice as much as the one Pyongyang conducted only eight months ago.

The North also boasted that the test was of a nuclear warhead that could be mounted on a missile.

South Korea, the United States, Japan, Russia and China all condemned the blast at the Punggye-ri nuclear site.

But the North's ruling party newspaper vowed yesterday not to submit to US nuclear "blackmail", and described the South's President Park Geun-Hye as a "dirty prostitute" for working with US forces.

"Gone are the days never to return when the US could make a unilateral nuclear blackmail against the DPRK," said Rodong Sinmun, using the country's official name.

The Security Council met at the request of Japan, South Korea and the United States to agree on a response, despite resistance from Pyongyang's sole ally China to calls for tougher measures.

Beijing strongly condemned the test. But its priority is to avoid the regime's collapse, which would create a crisis on its border and potentially shift the balance of power on the Korean peninsula toward the United States.