North Korea's state news agency (KCNA) said Mr. Kim told Chinese diplomat Wang Jiarui that talks can resume anytime, provided the United States shows what Mr. Kim called sincerity.

Mr. Wang later told reporters that Mr. Kim hoped that all sides in the talks will make efforts to create the appropriate conditions.

U.S. State Department spokesman Richard Boucher says the other five nations are all ready to re-start negotiations without Pyongyang's preconditions.

Richard Boucher

"It's only North Korea that claims current conditions are unfavorable.  For our part, the United States stands ready to return to the talks to discuss the proposals that have been on the table since June," he said.

U.S. officials say that they are looking forward to learning more about Mr. Wang's visit to Pyongyang.

In Seoul, the U.S. Ambassador to South Korea, Christopher Hill, urged the five other parties to coordinate their efforts, to pressure Pyongyang to return to the table.

"To give up their nuclear programs, they are going to seek something and what they need to do is come to the table and respond to our proposal and tell us what they are looking for," he said.

China's foreign ministry official who deals with the nuclear issue, Ning Fukui, said the outlook for six-party talks still faced "opportunities and challenges."

Since 2003, the U.S., China, Japan, Russia and the two Koreas have held three rounds of talks aimed at persuading the North to abandon its nuclear activities. A fourth round, scheduled for last September, was canceled when North Korea pulled out of the process, citing what it said was a hostile attitude by the U.S. 

China has hosted all the talks. However, they have made little progress in diffusing tensions. The United States wants a verifiable nuclear freeze and weapons dismantlement as part of any deal. North Korea says it remains convinced Washington wants to overthrow the Communist state, and claims it needs nuclear arms for self-defense.