According to China's official news media, Choi's remarks came in response to Xi's call for a nuclear-free Korean Peninsula. Xi was quoted by Xinhua news service as saying that denuclearization of the Korean Peninsula should be met "no matter how the situation would evolve."

The Seoul government sees North Korea's policy direction as expressed through Choe lacks specifics concerning the desired goal of it and other regional players to make the Korean Peninsula nuclear-free.

"Unlike China, North Korea did not say the word 'denuclearization,'" a high-ranking South Korean government official said. "We have to wait a little longer and keep watch over the words and behavior of North Korea regarding nuclear issues."

The official also said it is "too early" to believe the truthfulness of Pyongyang's intentions to return to the six-party forum.

The South Korean ruling Saenuri party also voiced skepticism, saying that Pyongyang should first give up its nuclear program before restarting the process of the six-party talks.

"The six-party talks are necessary. But North Korea should first reveal its intent to denuclearize," the ruling party spokeswoman, Min Hyun-joo, said in a press release.

Earlier in the day, the North's state media reported that in his personal letter delivered to Xi through his special envoy, the North Korean leader underlined the need to foster and consolidate the traditional friendship between the two countries.

Kim Jong-un's gesture was seen as part of a greater effort to mend fences with China. Pyongyang angered Beijing by raising tensions in the region by continuing to pursue a nuclear program despite China's repeated call against it.

"Kim Jong-un in his personal letter underlined the need to carry forward and consolidate the traditional DPRK-China friendship provided and cultivated by the revolutionaries of the elder generation of the two countries," the North's Korean Central News Agency said in a report, monitored in Seoul.

"Xi Jinping expressed deep thanks for this and asked Choe Ryong-hae to convey his cordial greetings to Kim Jong-un," the KCNA report said.

The South Korean official also noted that it is still too early to judge whether an estranged relationship between the two communist countries has been mended.

Meanwhile, Choe returned home on Friday after his meeting with the Chinese leader, the KCNA added.

North Korea walked away from the six-party nuclear disarmament talks in 2009 over disagreements on how to verify steps the North was meant to take to end its nuclear programs.

The talks involve the two Koreas, the United States, China, Japan and Russia. (Yonhap News)