North Korea may not be ready to hold "serious and productive" discussions with countries involved in the long-stalled talks on its nuclear programs, a top U.S. diplomat said Friday.

Ambassador Sung Kim, the U.S. special representative for North Korea policy, met with his Chinese counterpart Wu Dawei in Beijing to discuss a range of issues including North Korea. Earlier this week, Kim had held trilateral talks with his South Korean and Japanese counterparts in Tokyo.

"I think the common position of all parties, including China and the U.S., is that we should look for an opportunity to have a substantive engagement with North Korea," Kim told reporters.

"The question is not what we are willing to do," Kim said. "The question is whether North Koreans are ready for any serious and productive discussions on the nuclear issue."

Asked about a South Korean media report that the U.S. offered North Korea a bilateral meeting in Beijing, shortly before Kim's trip this week, Kim replied, "I don't want to get into details about diplomatic communications, but North Koreans are aware that I will be in Beijing."

"I think they understood that this will be an opportunity for a substantive dialogue on the nuclear issue," Kim said, adding that there was no meeting with North Korean officials in Beijing this week. (Yonhap)