North Korea has cautiously welcomed a proposal by the US to end the 20-month impasse over its nuclear programme.
Washington offered aid in return for a nuclear freeze
A statement by the North Korean Foreign Ministry said some common ground was reached at six-nation talks which ended on Saturday in Beijing.
But it stressed that "big differences" remained, including disagreement over whether the North was harbouring a secret enriched uranium programme.
All parties have agreed in principle to meet again in September.
The six nations - the US, China, Japan, Russia and the two Koreas - had been discussing a US proposal to provide North Korea with much-needed fuel aid in return for a freeze and eventual dismantlement of its nuclear facilities.
It was the first detailed proposal from Washington on ending the nuclear deadlock since President George W Bush took office.
"Unlike the previous talks, each party advanced various proposals and ways, and had a discussion on them in a sincere atmosphere at the talks," the North Korean statement said.
BREAKING THE DEADLOCK?
US reportedly ready to agree to fuel aid and 'provisional guarantee' not to attack
Talks on lifting US sanctions also on offer
In return, North must seal nuclear facilities within 3 months
Fuel aid and talks will continue if North then dismantles facilities
"Some common elements helpful to making progress in the talks were found there," it said.
However, it said differences include the US proposal that the North would have only three months to freeze its nuclear facilities in return for fuel aid and talks on lifting US sanctions.
North Korea said this timeframe "could not be supported by anyone, as it totally lacked scientific and realistic nature".
The statement also said Washington should drop its "unreasonable assertion" about the existence of an enriched uranium programme and said mutual distrust and suspicion remained.
US officials told reporters there had been "no breakthroughs" at the talks.
"The process is moving along, but we are not ready to point to successes," an unnamed official said, adding that there had been a lack of "tangible, boastable progress".
Two previous rounds of talks also ended inconclusively.
But North Korea was publicly far more negative following those.
It spoke of a "fundamental difference" between Pyongyang and Washington and "no substantive and positive result" after the February talks.
After the first round of talks, in August 2003, North Korea dismissed the US' demand for its nuclear disarmament as a "brigandish-like demand beyond the tolerance limit".