Working group delegations to six-nation talks on the bitter standoff left Beijing Saturday after the United States and North Korea appeared to harden their positions at the talks, which began on Wednesday.
A North Korean foreign ministry spokesman said the United States was wasting time and this could lead the state to build up his nuclear deterrent, the official KCNA news agency reported.
"If the US persistently seeks to waste time, pressurizing the DPRK (North Korea) to change its political system and disarm itself under the signboard of 'peaceful talks', the DPRK will...use it as a means for building stronger nuclear deterrent force," the spokesman was quoted saying.
The low-level discussions were seeking to set the agenda for a third round of higher, vice ministerial talks agreed to when the delegations from the two Koreas, China, the United States, Japan and Russia last met in February.
China's representative to the meeting, Ning Fukui, said another working-level group meeting would be held before the slated third round of vice ministerial meetings due before the end of June, Xinhua news agency said.
"It is the hope of the Chinese side that all parties would hold consultations in a flexible, practical and patient manner and explore ways to settle the issue," Ning said.
The key sticking point has appeared to be whether North Korea should give up its entire nuclear program, or only the military part, in exchange for economic aid and security guarantees.
Washington wants a clear-cut commitment from the North for a "complete, verifiable and irreversible dismantlement" before any compensation can be considered.
US Secretary of State Colin Powell said in Washington Friday that the three days of talks produced "no particular breakthroughs," and further urged the international community to increase pressure on Pyongyang to back down from its nuclear weapons ambitions.
In a further development, Japanese Prime Minister Junichiro Koizumi announced Friday that he would meet North Korean leader Kim Jong-Il in Pyongyang next week to discuss the abduction of Japanese citizens and the regime's nuclear arms ambitions.
He said Japan had informed the United States, China and South Korea of his planned visit to the Stalinist state.
Before returning to Pyongyang from Beijing, the North Korean chief delegate Li Kun said his country would continue to participate in the talks, Yonhap news agency said.
"We have had serious discussions at the talks. We confirmed that a common view has been formed that there would be reward for us in return for freezing the nuclear weapons program."
"Another consensus is that the US demand for CVID (complete, verifiable, irreversible dismantlement of nuclear programs) is an obstacle to progress in negotiation."
China's leading People's Daily newspaper said that during the working-level talks both the United States and North Korea hardened their positions with neither side willing to give in.
"Without aid and security guarantees, North Korea cannot consider the US demand for the complete verifiable and irreversible dismantling of its nuclear program," the paper quoted a North Korean official as saying.