South Korea's top nuclear envoy is seeking to visit Washington as early as next week to discuss the launch of a "working group" with the United States for closer coordination on North Korea's denuclearization, diplomatic sources in Seoul said Wednesday.

Seoul's special representative for Korean Peninsula peace and security affairs Lee Do-hoon has been coordinating a schedule for talks with his US counterpart Stephen Biegun to fine-tune details over the formation of the dialogue channel.

During Biegun's visit to Seoul late last month, the allies agreed to establish the working group for "regular, systemic and formal" communication on denuclearization, anti-Pyongyang sanctions and inter-Korean exchanges.

The agreement came amid speculation that Seoul and Washington were at odds over the pace of diplomacy with the communist state that has yet to take tangible denuclearization steps, such as a full declaration of its nuclear and missile programs.

Should they meet, Lee and Biegun could also discuss other issues, such as the prospect of high-level talks between US Secretary of State Mike Pompeo and his North Korean counterpart Kim Yong-chol, which were set for Thursday last week but were canceled due to the North's request.

Observers said that Lee's trip to Washington could be deferred should the high-level talks be rearranged. (Yonhap)