Deputy Foreign Minister Alexander Losyukov criticized the United States, one of the six parties to the talks, for its inflexible negotiating stance.
"The situation is still not very promising, as the Americans are rigidly sticking to their position - they will not make compromise steps towards North Korea until there is full disclosure" of Pyongyang's nuclear activities, the diplomat told journalists in Moscow.
"We know that the Americans have very strict demands on North Korea. And since problems have arisen, they must be brought forward to be considered by all participants," said Losyukov, Russia's envoy to the talks, also involving South Korea, Japan, and China.
Last November, Pyongyang provided a list of its nuclear programs to the United States, which Washington considers to be incomplete.
Losyukov said that apart from Pyongyang and Washington, none of the parties to talks know what has been disclosed on the North's nuclear activities, as dialogue on this issue is being conducted solely between those two countries.
"It would therefore be good for everyone to gather and receive full information," he said.
North Korea, which tested a nuclear bomb in October 2006, closed down its Yongbyon nuclear reactor in July under a February six-nation deal.
Earlier this week, however, a U.S. intelligence report said that North Korea remained a nuclear proliferation risk and was probably still working on developing uranium enrichment capability.
North Korea was to halt its nuclear programs and provide complete information on nuclear activities by the end of 2007, in exchange for economic and political concessions. However, the North missed the deadline, causing negotiations to stall.
Pyongyang earlier accused the U.S. of failing to strike it off the list of states sponsoring terrorism and lift related trade restrictions, Washington's obligations under the November 2006 six-party deal.
The latest round of six-nation talks ended in December in Beijing with no breakthroughs.
