China's top nuclear envoy Wu Dawei left Thursday for a four-nation tour to discuss the North Korean nuclear issue.

Chinese Foreign Ministry spokesman Qin Gang told a regular news briefing that Wu will visit Russia, the United States, Japan and South Korea to exchange views on the North Korean nuclear issue and the situation in northeast Asia.

The visit is seen as a signal that China has launched efforts to resume the deadlocked six-party nuclear talks.

During the trip, diplomatic sources in Beijing say Wu will coordinate the positions of each country, explore ways to resume the six-party nuclear talks and make contact with North Korea.

The Chinese envoy will reportedly hold intensive discussion on various issues, including holding five-party talks, when he visits Seoul from July 12th to 14th.