North Korea has spurned US and Japanese demands that it scrap all of its nuclear programmes at six-party talks in Beijing that now appear deadlocked, a diplomatic source said.
North Korea rejected the demands and denied having a uranium enrichment programme, the source close to the talks between the two Koreas, the United States, Japan, Russia and China said.
The source said North Korea was locked in a furious dispute, particularly with the United States and Japan, over the "scope of the abandonment" of its nuclear ambitions.
Host China, Pyongyang's closest ally, attempted to mediate, saying the reclusive North could be entitled to have nuclear reactors for civilian use if it rejoined the nuclear non-proliferation treaty (NPT).
North Korea quit the treaty and expelled UN inspectors after the United States accused it of having a clandestine nuclear weapons programme in October 2002.
Japanese Foreign Minister Nobutaka Machimura
The crisis has brewed since and spawned four rounds of talks in Bejiing.
"I don't know where we go with this," said the chief US delegate, Assistant Secretary of State Christopher Hill. His South Korean counterpart, Song Min-soon, added: "In the current situation, we are almost running out of wisdom."
"I can't say discussions on the wording of the agreement are going smoothly," Japanese Foreign Minister Nobutaka Machimur said. "North Korea continues to deny that it has a uranium enrichment program."
US officials said in late 2002 that the North admitted to violating a 1994 deal by embarking on a secret uranium enrichment program, sparking the latest nuclear standoff.
In February, North Korea claimed it had nuclear weapons and has since taken steps that would allow it to harvest more plutonium for possible use in bombs.
Many experts believe the North already has enough weapons-grade material for about a half-dozen atomic weapons.