Six-party talks on the North Korean nuclear crisis ended on Saturday without a breakthrough but a senior US official said the meetings had advanced Washington's agenda of disarming Pyongyang.
Chinese Foreign Minister Li Zhaoxing closed the four-day session saying all sides had agreed to set up a working group and hold the next set of talks in Beijing before the end of June.
"Differences, even serious differences, still exist," Li said at the closing ceremony, without specifying what gaps remained.
China's chief negotiator, Wang Yi, cited an "extreme lack of trust" between the US and North Korean side and said further discussions were needed on the scope of both the North's proposal to freeze its nuclear programmes and the US demand for dismantling all atomic arms schemes.
But a senior US official declared the talks that also involved South Korea, Japan and Russia "very successful", saying all but Pyongyang had agreed to the goal of a nuclear-free North.
"The event has exceeded my expectations in a very important respect. It's been very successful in moving the agenda towards our goal of complete, verifiable and irreversible dismantling (CVID) of DPRK nuclear programmes," the US official said.
"CVID is now more on the table than ever."
Russia's chief delegate, Alexander Losyukov, said the talks achieved "modest" results. But he called the working groups "a reasonable base for the continuation of discussions of those problems arising from the different positions".
Analysts said, however, that Washington and Pyongyang could both dig in their heels in this US presidential election year.
China's Li said the second round featured substantial dialogue and made "a big step forward".
"The road is longer and more bumpy. But time is on our side. Time is on the side of peace," Li said.
North Korea, whose 11th-hour rejection of language in a proposed agreement prolonged the talks for hours and prevented the parties from signing a joint declaration, repeated its denial that it had an enriched uranium weapons programme.
"We believe the insistence of the raising of the HEU (highly enriched uranium) issue by the US side is very much related to the position of the US Bush administration, who based this assertion on false information," Kim Gye-gwan, head of the North Korean delegation, told reporters after the talks.
A Japanese diplomat said late on Friday the United States had not shown any evidence the North had such a programme.
The US official said the American goal of completely dismantling all of the North's nuclear arms programmes had "essentially been accepted by all of the participants except the DPRK". DPRK stands for the Democratic People's Republic of Korea.
"The DPRK did say and has said that it will dismantle its nuclear programmes. The devil, of course, is in the details," said the official.