A special envoy of Chinese President Hu Jintao left Wednesday for a visit to the United States and Russia amid regional tensions over North Korea's claims of a nuclear test this week, China's foreign ministry said.
It did not give any other details on who Tang will meet or what will be discussed.
The trip comes two days after the North claimed that it had tested an atomic bomb. On Wednesday, the regime fuelled regional tensions by saying that impending sanctions would be an act of war and threatened more nuclear tests.
China has indicated that its patience is wearing thin and has joined other Security Council members in unanimously condemning the North's decision to carry out a test.
But as Pyongyang's last major ally, Beijing has not agreed to severe sanctions backed by Washington.