"We expect a complete and accurate declaration from North Korea," Rice said at a news conference alongside Canadian Foreign Minister Maxime Bernier.

She noted that Sung Kim, the US State Department's top expert on Korean affairs, was in North Korea leading a US team of experts supervising the work at the Yongbyon complex.

"I'm not following, moment by moment, what he's finding there. But I would hope that the North Koreans understand that a lot is at stake here," the chief US diplomat said.

"That, in fact, we have made good progress on the disabling of the Yongbyon facility and its associated facilities," Rice said. "We have made good progress, in terms of beginning the denuclearization of the Korean Peninsula."

"But this is now a crucial step, because if we are to move forward, and if we are to move forward on all of the benefits that would come to North Korea through the successful completion of this second phase, we really must have an accurate declaration," she said.

North Korea agreed in a six-nation pact to disable and declare all of its nuclear programs by December 31, in return for energy aid and the promise of future major diplomatic concessions.

But the process has reportedly hit a key problem -- the North's refusal to address its suspected highly enriched uranium weapons program to the satisfaction of the United States.

President George W. Bush this month wrote to North Korean leader Kim Jong-Il, urging him to fully disclose his nuclear programs.

But top US officials have suggested that the December 31 deadline for a full declaration may slip into early 2008.

The six-party talks group the two Koreas, the United States, China, Russia and Japan.