President Park Geun-hye and Chinese President Xi Jinping are likely to adopt a joint declaration that includes the "denuclearization" of North Korea, after their summit talks set for late next month, a diplomatic source in Seoul said Thursday.

South Korea and China have been in the midst of fine-tuning the language to be used in the joint declaration, the source said on the condition of anonymity. Park is scheduled to visit China late next month for her first summit with Xi since taking office in February.

"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."

If included, it would demonstrate the new Chinese government's willingness to step up efforts to get North Korea to give up its nuclear weapons program, according to the source.

In a meeting with Xi in Beijing last week, a North Korean special envoy, sent by North Korean leader Kim Jong-un, said Pyongyang is willing to rejoin the long-stalled six-nation talks on its nuclear weapons program, according to Chinese media reports.

During the meeting, Xi told the North's envoy, Vice Marshal Choe Ryong-hae, that denuclearization of the Korean Peninsula should be achieved no matter how the situation changes.

Nonetheless, strong doubts persist about the North's true intentions after its media conspicuously failed to mention the envoy's remarks made to Xi concerning the six-party talks. The forum, which involves the two Koreas, the U.S., China, Japan and Russia, has been suspended since late 2008.

North Korea quit the six-party forum in a dispute over how to verify steps it was supposed to take to disarm. Early this year, the North conducted its third nuclear test and declared that its nuclear programs are non-negotiable. (Yonhap News)