North Korean leader Kim Jong-un may not be able to visit China on his first foreign trip if there is no progress in diplomatic efforts to persuade the North to give up its nuclear ambitions, South Korea's ambassador to China said Wednesday.

Amb. Kwon Young-se was also cautious when talking about the possibility of a visit by Kim to Russia in May, saying it is too early to conclude that Kim's trip to Russia would take place.

Kim took the helm of the authoritarian state in late 2011 after his father, Kim Jong-il, died. China is North Korea's ideological ally and economic lifeline, but their political ties remain strained, particularly after the North's third nuclear test in early 2013.

Russia has said that Kim would be among those attending the May 9th ceremony marking the 70th anniversary of the Soviet victory over Nazi Germany in World War II.

"I believe that a visit by Kim Jong-un to China is connected to the issue of denuclearization," Kwon told Yonhap News Agency in an interview.

"From the perspective of China, there is a clear aspect that it would be burdensome to conduct a highest-level exchange with North Korea at a time when North Korea shows no progress in the nuclear issue," Kwon said.

Asked about the possibility of Kim's visit to Russia in May, Kwon replied, "No one can speak conclusively."

Analysts say North Korea won't give up its nuclear weapons program because it would prolong the Kim regime and help obtain political and economic benefits from the international community.

With China cold-shouldering the nuclear policy of North Korea, Pyongyang is seeking to deepen both diplomatic and economic ties with Russia.

Russian President Vladimir Putin, who has been under intense pressure over the conflict in Ukraine, is also eager to bolster ties with North Korea in an apparent effort against America's pivot to Asia.

Kwon said China is "firmly committed" to achieving the goal of denuclearizing North Korea.

"As for North Korea's nuclear issue, South Korea and China have been in close communication," Kwon said. (Yonhap)