The North Korean nuclear disarmament talks drag into a 10th day with fresh claims the North Korean delegation is still refusing to compromise.
After nine days of intense negotiations there are increasing concerns the sides remain too far apart to reach a consensus.
As he headed to a fresh round of meetings Thursday morning, Christopher Hill, the top U.S. envoy to the talks, said there is a lingering dispute over verification.
"We cannot have a situation where the DPRK [Democratic People's Republic of Korea - North Korea] pretends to abandon its nuclear program and we pretend to believe them," said Mr. Hill. "We need to have a situation where we know precisely what they have agreed to do, exactly what they have agreed to abandon."
China has been working on a fourth draft of a proposed joint statement for the six countries in the talks.
Wednesday, Mr. Hill said North Korea is the lone holdout refusing to accept the latest Chinese proposal, which he described as a good deal for the North Koreans.
Song Min-soon, the lead South Korean envoy, made a similar comment Thursday morning. He says the North Korean position remains out of line, which is why the talks have not ended.
The negotiations, which include North and South Korea, the United States, Russia, Japan and China, are aimed at persuading the Pyongyang government to give up its nuclear weapons program.
The nuclear crisis erupted in 2002 when North Korea said it had broken an earlier agreement on halting nuclear development programs.
Three rounds of previous talks failed to resolve the conflict. North Korea is reportedly seeking significant economic aid and U.S. security guarantees before it dismantles its nuclear weapons.