South Korea plans to ask China to exercise more leverage to get North Korea to change its course on its nuclear weapons program and return to the negotiating table when the top nuclear envoys from Seoul and Beijing meet late Thursday, a South Korean diplomat said.
  

Hwang Joon-kook, South Korea's special representative for Korean Peninsula peace and security affairs, is set to hold talks with his Chinese counterpart, Wu Dawei, in Beijing.
  

The talks between Hwang and Wu come as North Korea appears to be preparing to launch a long-range rocket, possibly in October, after completing the upgrade of a missile launch site.
  

"It has been increasingly clear that North Korea won't change course as North Korea has rejected any dialogue on its nuclear program. So, it is time for the Chinese side to play a more active role in reining in the North," said the diplomat with knowledge of the talks.
  

China is North Korea's economic lifeline, but it has been reluctant to use leverage over the ally because it could lead to the North's collapse and instability on its border.
  

The six-party talks on North Korea's nuclear program, involving the two Koreas, the U.S., China, Russia and Japan, have been stalled since late 2008.
  

Diplomatic efforts to revive the multilateral talks have produced no results so far and North Korea conducted its third and most powerful nuclear test in 2013. (Yonhap)