The source told Yonhap if the "denuclearization" word is adopted in the document to be issued after the summit between South Korean President Park Geun-hye and her Chinese host Xi Jinping, it would indicate China's new leadership led by Xi is willing to step up efforts to convince its ally North Korea to scrap its nuclear weapons program.
Park, who became president in February after her election victory, is scheduled to visit China next month for a summit with the new Chinese president.
The source told Yonhap the two sides are currently working on the declaration's language.
"The North Korean nuclear issue is an important part of the joint declaration," the source said. "There is a high possibility that the word denuclearization will be included in the joint declaration in regard to solving the nuclear issue of North Korea."
Last week, a special envoy sent to China by North Korean leader Kim Jong Un had been quoted as saying his country is willing to rejoin the long-stalled six-nation talks on its nuclear program. At that meeting, Xi had been quoted as telling the visitor denuclearization of the Korean Peninsula should be achieved regardless of the situation.
The six-nation talks among the two Koreas, China, Japan, Russia and the United States calling on the North to end its nuclear program in exchange for massive aid have remained stalled since late 2008 after the North walked out following a dispute over how to verify its disarmament actions. On Feb. 12 this year, the North conducted its third nuclear test.