Seoul's top nuclear envoy will travel to China on Sunday for meetings with his counterpart and experts on Korea, the foreign ministry said.
  

Hwang Joon-kook will be in Shanghai until Tuesday and visit Beijing from Tuesday to Friday for talks with university scholars, think tank researchers and journalists, among other experts.
  

Hwang also plans to meet with Wu Dawei, China's special representative for Korean Peninsula Affairs.
  

Both Hwang and Wu are their governments' top envoys to the now-stalled six-way talks on Pyongyang's nuclear weapons drive. The negotiations also involve the U.S., Japan and Russia.
  

A South Korean government source said Hwang's trip comes at a key juncture, with consultations between Seoul and Beijing on Pyongyang rendered more necessary following the recent agreement on the Iranian nuclear issue.
  

"China must be thinking long and hard about its relationship with North Korea," the source said. "It's the right time for us to share our thoughts with China."
  

China, as North Korea's economic lifeline and diplomatic backer, appears to hold the key to pressuring Pyongyang to return to the six-party talks. China has invited North Korean leader Kim Jong-un to its Sept. 3 celebrations of the 70th anniversary of the end of World War II. (Yonhap)