North Korea's ruling party called for the staging of a "high-intensity" action and further long-range rocket launches, state media reported Tuesday, ahead of an expected nuclear test.

The report on a meeting of the Korean Workers' Party politburo made no specific reference to a nuclear detonation, which some analysts are now suggesting may not be as imminent as initially believed.

The politburo session "called for staging an all-out action of high intensity," the Korean Central News Agency (KCNA) said.

It also stressed the need to continue launching satellites and "powerful long-range rockets," KCNA said.

The statement carried strong echoes of the initial announcement last month by the North's top military body, the National Defence Commission, that it would conduct a "high-level nuclear test" and further rocket launches.

That announcement was seen as signalling an imminent test, with some observers predicting a date that would coincide with the late North Korean leader Kim Jong-il's birthday on February 16.

Satellite imagery analysis of the North's remote nuclear test site, as well as US and South Korean intelligence reports, all concluded that the North has completed all necessary test preparations.

But doubts were raised after a North Korean state media outlet last week said the United States and South Korea had "jumped to conclusions" that a test was imminent.

Paik Hak-Soon, a North Korea expert at the Sejong Institute think-tank, said the vague language being used by Pyongyang suggested it might be open to negotiating a way of stepping back from a test.

"They are basically telling the US, 'Look. The nuclear test may not be as imminent as you believe. We can stage the test tomorrow, next month, or even far later depending on how you guys deal with us'," Paik told AFP.

Pyongyang has said any test would be a direct response to the UN Security Council's adoption of a US-proposed resolution that condemned the North's rocket launch in December and expanded existing sanctions.

North Korea insists the rocket launch was a scientific mission aimed at putting a satellite into an orbit.

But the United States and many other countries viewed it as a disguised ballistic missile test, banned under UN resolutions triggered by Pyongyang's previous nuclear tests in 2006 and 2009.

The latest Security Council resolution threatened "significant action" if the North went ahead with a third nuclear test, and the international community has issued repeated appeals and warnings over the past month.

These have included unusually strong warnings from China, which is the North's only major ally and has shielded its neighbour from harsh sanctions in the past.

Chinese state media has said Beijing would exact a "heavy price" from North Korea in the event of a nuclear test, and warned of a "breakdown" in a relationship that provides Pyongyang a crucial economic lifeline.

On Monday, South Korea's Yonhap News agency said no activity had been picked up at the North's nuclear test site for several days, suggesting manpower may have been withdrawn ahead of a test.

But some officials noted that the inactivity might just be linked to the Lunar New Year holiday which fell at the weekend.