Stoking regional jitters, the United States said it had detected possible preparations for a nuclear test and a leading South Korean newspaper predicted the communist regime could detonate a bomb as early as next week.

Amid divisions at the UN Security Council, a senior Japanese official on a visit to Washington said the allies supported invoking a chapter of the UN Charter authorizing far-reaching sanctions or theoretically military action.

"In the event that North Korea conducts a nuclear test, it would inevitably be necessary to seek a resolution with Chapter VII at the UN Security Council," vice foreign minister Shotaro Yachi said.

New Japanese Prime Minister Shinzo Abe, well known for his hard line on Pyongyang, is set on Sunday to visit China and South Korea, which have warned against further isolating their communist neighbour.

"A good discussion has to take place at the United Nations to make the North realise that if the country continues taking such actions it would be in an even more severe situation," Abe told parliament.

North Korea on Tuesday dramatically raised the stakes in the long-running standoff over its nuclear programme by announcing it would test a bomb at an unspecified date.

Chosun Sinbo, a newspaper published by ethnic Koreans in Japan and seen as representing Pyongyang's view, warned Thursday that a test was "unavoidable" unless the United States adopted a more conciliatory stance.

"The DPRK (North Korea) statement on a nuclear test is not empty talk but clearly premised on action," the newspaper said in a dispatch from Pyongyang, according to its Korean-language website.

Japan and the United States already have imposed most of the sanctions at their disposal against the impoverished nation, which conducts the bulk of its trade with China and South Korea.

The North, which last year declared itself nuclear-armed, has boycotted six-nation disarmament talks since November to protest one set of US sanctions aimed at blocking it from money laundering and counterfeiting.

But even after Tuesday's statement there was no sign of unanimity at the Security Council, which rebutted Japanese and US attempts to invoke Chapter VII after North Korea test-fired seven missiles in July.

US ambassador John Bolton spoke of "division" within the body, saying the regime's "protectors" -- implying veto-wielding Moscow and Beijing -- opposed a tough line.

His Chinese counterpart Wang Guangya took exception, urging "less mistrust" between Washing-ton and Pyongyang.