The editorial in Rodong Sinmun on Tuesday followed a statement on Monday from the North Korean foreign ministry that said Pyongyang was seriously reconsidering its role in the talks because of what it saw as a concerted campaign to topple the North's ruling system.
Yet, while the rhetorical volume rose, North Korea made a gesture to the South by inviting a minister to a factory-opening ceremony on Wednesday, just over the border in the North.
On the six-party talks, Rodong Sinmun said North Korea wanted to step up the process, but not at any price.
"It is not the aim of the talks to keep them go on for the mere form's sake," said Rodong Sinmun, which is the ruling communist party daily. "It is useless to hold talks, even a hundred times, without producing any substantial results."
The official KCNA news agency published an English-language text of the editorial and added its own commentary, reiterating Pyongyang's demand that South Korea's own past nuclear research should be discussed before North Korea's atomic programmes are tackled.
The International Atomic Energy Agency said last month South Korea had conducted experiments in the past that produced near weapons-grade fissile material in minute quantities. But it stopped short of referring the case to the UN Security Council.
KCNA said this was a double standard and the North could not take part in talks that focused only on North Korean plans.
The IAEA said the South also
conducted nuclear experiments
"It is as clear as noonday that such talks will get one nowhere," it said.
North and South Korea, still technically at war after their 1950-53 conflict ended in a truce and not a peace pact, have met the United States, Japan, Russia and China for three rounds of talks on the North's nuclear ambitions, but have made little apparent progress.
A fourth round scheduled for September has never happened.
Taken together, the newspaper, agency and ministry comments represented a hardening of Pyongyang's position. But the North has in the past used strident public rhetoric even when approaching negotiations or making concessions.
Unification Minister Chung Dong-young's first visit to the North - to watch the opening of the first factory at the Kaesong industrial park - will be the highest-level contact since Pyongyang broke off talks with Seoul after hundreds of North Korean refugees were airlifted out of Vietnam earlier this year.
It was not immediately clear whether he would meet similar ranking North Korean officials or hold formal talks. Either way, it marks a potential shift at a time of deadlock.
The editorial accused the US of
being 'clumsy and nasty'
Rodong Sinmun, whose comments carry a high-level imprimatur, said Washington was being "clumsy and nasty" for trying to blame North Korea for stalling the six-party talks.
It said bilateral contacts in New York had shown that Washington wanted the North to renounce all its nuclear activities, including peaceful research, and was persisting in what Pyongyang calls a hostile policy towards North Korea's leadership.
"Should the US persist in this wrong stand, it would be hard to resume the talks," the daily said.
Fissures in South
The five regional powers are seeking to persuade the North to ditch its nuclear weapons ambitions in return for aid and security guarantees.
Rodong Sinmun reiterated that Pyongyang was waiting to see the shape of re-elected US President George Bush's administration and North Korea policy before deciding whether to attend a fourth round.
The independent Brussels-based International Crisis Group said in a report released on Tuesday, fissures were forming in the South Korean public over how to handle the North.
It said younger people, including those in power under President Roh Moo-hyun, were less easily swayed by appeals to anti-communism than those who lived through the Korean War.
"Significant generational and political shifts have transformed views in ways that could undermine US policy in the region unless Washington develops a better understanding of the situation in Seoul," it said.