A file photo of chief South Korean envoy for six-party dialogue Kim Hong-Kyun. Photo: [Yonhap News]

South Korea's top envoy at the long-stalled six-party talks will visit China on Friday to discuss North Korea's nuclear program with his Chinese counterpart.

Kim Hong-Kyun, chief South Korean envoy for six-party dialogue to denuclearize the Korean peninsula, will come to China to meet with Wu Dawei, China's special representative on Korean peninsula affairs.

Kim Hong-Kyun and Wu will assess the Korean peninsula situation based on the results of China-South Korea summit held in Washington in March.

The two diplomats will also discuss comprehensive cooperation between the two countries regarding North Korea's nuclear program.

The six-party talks, which involve South Korea, North Korea, China, the United States, Russia and Japan, have been stalled since late 2008.

The United States Thursday also sent a special envoy for North Korean affairs to China.

Sung Kim met with Wu Dawei after making a stop in Seoul to meet South Korean and Japanese officials.

Sung Kim is working to determine what response will be appropriate should Pyongyang test another nuclear weapon.

"The US and China remain united in our firm opposition to North Korea's proactive and irresponsible behavior, and on the importance of implementing UN Security Council Resolution 2270 fully and faithfully, and of course our common pursuit of complete denuclearization of Korean peninsula."

North Korea is already subjected to international sanctions following a previous nuclear test and launch of a long-range rocket earlier this year.

Those sanctions include a significant ban on the import and export of products to and from North Korea and China.

Increased activity has been reported around North Korea's main nuclear testing site in the country's northeast, leading to speculation Pyongyang's leadership is preparing another nuclear weapons test ahead of a key political meeting next month.