A sticking point in talks has been how to verify North Korea's disarmament
Top US nuclear envoy Christopher Hill has met his Chinese counterpart in Beijing, in the latest round of talks over North Korea's nuclear programme.
The meeting follows moves by Pyongyang to reverse its promised disarmament.
North Korea accuses the US of failing to meet its obligations under a six-nation aid-for-disarmament deal.
Washington says it will take the North off its list of state sponsors of terrorism after it complies fully with disarmament requirements.
Earlier this week, North Korea began moving some disassembled parts back to the key reactor at Yongbyon, which is has pledged to dismantle.
On Saturday Mr Hill met Wu Dawei, who represents China in the six-nation talks - which also involve both Koreas, Japan and Russia.
On Friday, after discussions with South Korean and Japanese officials, he said the North's nuclear declarations needed to be verified.
"I think there's a lot of support within the six-party process for getting this done," he said.
He added that he had no plans for talks with North Korean officials before flying back to Washington.
Stand-off with US
North Korea agreed in February 2007 to give up its nuclear ambitions in return for aid and diplomatic concessions.
In June it handed over long-awaited details of its nuclear facilities. In return, it expected the US to remove it from the list of state sponsors of terrorism.
But the US wants North Korea to agree to a process of verifying the information - something the two sides have so far failed to do.
Last week North Korea announced it had halted disabling work at its Yongbyon nuclear reactor. Officials from countries negotiating with North Korea now say that it is moving some equipment out of storage and back to the plant.
In a separate development, North Korea has announced that it will delay a fresh probe into the abduction of Japanese citizens in the 1970s and 1980s to train spies.
In 2002, it admitted that it had kidnapped 13 Japanese citizens. Five have been returned and Pyongyang says the other eight died.
But Japan insists that North Korea abducted more people than it acknowledges, and wants more proof of the eight deaths.
North Korea said it would hold off on the probe until it established the policies of the new Japanese leader.
Prime Minister Yasuo Fukuda announced his resignation earlier this week and the current favourite to replace him is the ruling party secretary-general, Taro Aso.
A well-known hawk, he has called for a tougher line towards North Korea - something that will worry the communist state.