North Korea should end its nuclear activities and allow U.N. nuclear inspectors to return to the North to monitor its Yongbyon nuclear complex as the first step toward complete denuclearization, Seoul's top nuclear envoy said Thursday.

The remarks by Hwang Joon-kook came as diplomatic efforts are under way to gauge Pyongyang's willingness to denuclearize before the long-stalled six-party talks resume.

Seoul and four nations involved in the six-party talks -- the United States, China, Japan and Russia -- have recently reached a consensus on conditions for resuming the denuclearization talks that also involve the North.

The five nations also shared the need to have "exploratory dialogue" with Pyongyang to test its sincerity about denuclearization, according to the foreign ministry.

"Now is the time to deliver the consensus by the five members to the North and seek to have so-called 'exploratory talks' with it," Hwang told a forum in Seoul. "If we can find Pyongyang's sincerity, the six-party talks can be resumed."

Hwang said that Pyongyang should end its ongoing nuclear activities and invite inspectors from the International Atomic Energy Agency (IAEA) to the North to resume their monitoring.

"North Korea should halt its plutonium and uranium nuclear activities at the Yongbyon nuclear reactor and allow the IAEA inspectors to return as the first step toward complete denuclearization."

North Korea expelled IAEA inspectors in 2009 and restarted its atomic activities after it walked out of the six-party talks in late 2008.

Pyongyang conducted nuclear tests in 2006, 2009 and 2013. Since the latest nuke test, North Korea has demanded the unconditional resumption of the six-party talks, but Seoul and Washington have claimed that the North should first show its sincerity about denuclearization.

Hwang said that Seoul is "willing" to have the talks with Pyongyang, but the ball is in the North's court as it should first demonstrate its willingness to give up its nuclear weapons.

"As North Korea has been advancing its nuclear capability, the next several years will be very important (for us to achieve the goal of the North's denuclearization)," he said. "If the North believes that time is on its side, it might be a miscalculation." (Yonhap)