"The proof of the pudding is in the eating," a senior State Department official said in response to reports from China that the North Koreans have had a new change of heart on the nuclear negotiations.

The official, who asked not to be named, said Pyongyang had issued a rash of declarations on the six-party talks that were broken off last year. "All of these statements don't amount to them showing up," he said.

State Department spokesman Richard Boucher reacted cautiously to the comments by a Chinese envoy returned from Pyongyang that the North Koreans were willing to resume talks "if the conditions are right."

He said the United States, China, South Korea, Japan and Russia were ready to return to the table without preconditions. "It's only North Korea that claims current conditions are unfavorable," he said.

Boucher said Secretary of State Condoleezza Rice, who was traveling in Europe, spoke with her Chinese counterpart Li Zhaoxing early Tuesday about the nuclear talks. But he gave no details.

"We'll seek to learn more from the Chinese regarding the Central Committee member, Wang Jiarui's, recent trip to Pyongyang," he said.

"And we will continue to look for willingness on the part of North Korea to come back and address these issues: address these issues diplomatically as we want to, address these issues peacefully as we want to."

Saturday, the United States and Japan joined in expressing "deep concern" over North Korea's withdrawal from the six-party talks and strongly urging it to return to the negotiations "without preconditions."

The White House, in commenting early Tuesday on the latest report of North Korea's position on the talks, did not react to Pyongyang's insistance on unspecified "conditions."

Spokesman Trent Duffy, speaking to reporters in Brussels, said only, "We've been clear, we want the North Koreans to return to the six-party talks."