China voted for a U.N. resolution last month that criticised Pyongyang for test-firing missiles in early July, with many regional powers saying the launch posed a threat to regional security.

Liu said the tests have had a negative impact on the politics on the Korean peninsula as well as North Korea.

North Korea defied international warnings and fired seven missiles on July 5, including its long-range Taepodong-2 missile.

The interview was conducted when Liu was in South Korea earlier this month.

During his stay in South Korea, Liu called on the North to return to stalled six-party talks on ending its nuclear weapons programme and for flexibility in the negotiations.