China says there are major disagreements among the six nations holding discussions on North Korea's nuclear weapons programs.
The working-level talks carried on for a second day at Beijing's Diaoyutai State Guesthouse, where delegates from China, Japan, North Korea, Russia, South Korea, and the United States met behind closed doors.
Chinese Foreign Ministry spokesman Liu Jianchao indicated to reporters that little progress had been made, but gave no details.
"There are still some major disagreements," he said. "We hope all parties can keep patient and flexible in the spirit of understanding and cooperation."
The United States this week reaffirmed its demands that it will accept nothing less than the complete, verifiable, and irreversible dismantling of North Korea's nuclear weapons programs. North Korea says it wants economic and security guarantees first.
Pyongyang has said it will go ahead with developing a nuclear deterrent force - which it says is needed to prevent a U.S. attack.
The working-level talks are to set an agenda for the next round of high-level negotiations on the nuclear dispute. Two earlier rounds of high-level negotiations ended inconclusively due to what analysts say was the lack of an agenda or a clear focus on what items were open for negotiation.
Chinese officials on Thursday said the issue of verification remains one of the main sticking points in the working-level negotiations. One official said each of the six delegations has a different opinion on how a dismantling process should be verified. The United States this week said the U.S. envoy to the talks might hold a separate meeting with the head of the North Korean delegation.
U.S. officials did not confirm whether that meeting took place on Thursday.
The dispute began more than 18 months ago, when the United States said Pyongyang had admitted having a secret nuclear weapons program, in violation of international accords. While North Korea has denied having the secret program, it has since restarted an older weapons project that had been frozen.
The working level talks are expected to continue for several days.