North Korea vowed Wednesday to tighten its hold on its "priceless" nuclear deterrent, confounding reports that it might be willing to resume multilateral talks on denuclearisation.

A lengthy front-page editorial in the North's ruling party daily Rodong Sinmun said a strong nuclear deterrent was the only guarantee of a "final victory" against the forces of imperialism.

"We will tighten our grip on this priceless nuclear treasure sword and carry out battles against imperialists with greater vigour," it said.

The editorial appeared days after Chinese state media said North Korean leader Kim Jong-Un had informed Chinese President Xi Jinping that Pyongyang would consider resuming six-party denuclearisation talks.

The Xinhua news agency said the message was sent in a letter that was hand delivered to Xi by Kim's personal envoy during a visit to Beijing last week.

North Korean state media had confirmed delivery of the letter but made no mention whatsoever of a dialogue proposal.

Wednesday's Rodong Sinmun editorial was the latest in a series of commentaries published in recent days that clearly reaffirmed the North's commitment to pursuing its nuclear weapons programme.

In a clear reference to Iraq and Libya, the newspaper said countries which lacked a sufficient deterrent or agreed to give up their nuclear weapons programmes had ended up as "victims of aggression".

The dialogue proposal as reported by Xinhua was greeted with scepticism in South Korea, where observers saw it as an effort to appease Beijing, rather than a genuine signal of intent.

North Korea has repeatedly declared that its programme to develop a viable nuclear deterrent is not open to negotiation.

Seoul and Washington insist that the North must demonstrate its commitment to abandoning its nuclear weapons programme in order for formal talks to begin.