Amid media reports that Washington proposed U.S.-North Korea talks in Beijing, the U.S. Special Representative for North Korea Policy, Sung Kim, pressed Pyongyang to show signs that it is ready for talks.

In a news conference in Beijing on Friday, Kim did not deny media discussions about the offer as he stressed that the U.S. has made it very clear publicly that it is open to dialogue with North Korea on nuclear issues.

While declining to elaborate on what he called "diplomatic communications" with North Korea, the U.S. chief nuclear negotiator said Pyongyang understood that his Beijing visit would be an opportunity for a substantive dialogue on the nuclear issue but no meeting took place. 

He stressed that the common position of all parties, including China is that they should look for an opportunity to have a substantive engagement with North Korea. He then pressured the North, saying it has shown no clear indication that it is ready for "serious and productive" discussions.

Kim's latest trip to China comes a month after his last visit in early December. He is said to have explained the result of the talks among top nuclear negotiators of South Korea, the U.S. and Japan, and delivered a message to China to play a bigger role to push Pyongyang to demonstrate its commitment to denuclearization through actions before the six-party talks can resume.

Before visiting China, Kim met with his South Korean and Japanese counterparts Hwang Joon-kook and Junichi Ihara in a trilateral meeting and bilateral meetings in Tokyo to discuss North Korea's nuclear issues.