A two-track regional security forum is to be held in Japan next month, involving government officials and scholars from the six nations engaged in multilateral talks on North Korea's denuclearization, sources said Sunday.

Since its inception in 1993, the Northeast Asia Cooperation Dialogue has served as a venue for informal dialogue among North Korea and its five dialogue partners on its nuclear program -- South Korea, the United States, China, Japan and Russia.

Organized by the University of California Institute on Global Conflict and Cooperation, the NEACD has brought together foreign and defense ministry officials, military experts and academics for "frank" discussions on regional security issues, including the North's nuclear programs.

Seoul is mulling pushing to hold "exploratory" talks with the other five members to gauge Pyongyang's willingness for denuclearization on the occasion of the forum if North Korea attends it.

The organizer is known to have sent an invitation to the North, but Pyongyang has not replied to it, according to the sources.

North Korea has been a regular participant of the forum since 2002, but the country has skipped it several times, mainly when it was held in Seoul. In September, the North also did not join the forum when it was held in the U.S.

"If the North attends the meeting, it could be a chance for holding exploratory discussions," a Seoul official said.

The NEACD can serve as a good venue for such exploratory talks as it sometimes brought together deputy nuclear chiefs from the participating nations in the past.

The six-party talks on Pyongyang's nuke program have been dormant since late 2008 as the North left the negotiating table.

Except for the North, South Korea and the other four nations to the six-party talks recently reached a consensus for exploratory talks to test the North's willingness for denuclearization. They have also shared the view for conditions for resuming the long-stalled talks.

Since a nuke test in 2013, 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 toward denuclearization. (Yonhap)