The following day, the two sides will have their second "working group" meeting, in which officials from the White House and South Korea's presidential office and unification ministry will also participate, he added.

The working group talks will be composed of two sessions: one on denuclearization largely between Lee and Biegun and the other on inter-Korean relations.

The second meeting will be led by Lee Dong-yeol, director-general for Korean Peninsula Peace regime at the ministry, and Alex Wong, deputy assistant secretary of state for North Korea and deputy special representative.

In the working group, the allies will closely coordinate various issues related to North Korea, including inter-Korean relations, and coordinate strategies for "substantive progress" in efforts toward denuclearization and a peace regime, the ministry said in a statement issued earlier in the day.

The meetings come amid growing concern about a drawn-out lull in denuclearization talks between Pyongyang and Washington.

President Donald Trump has openly indicated that he's in no hurry for dialogue, while North Korea's foreign ministry has warned that it won't wait for a long time.

In a statement issued Sunday, a senior policy researcher at North Korea's Ministry of Foreign Affairs, said if the US sticks to sanctions and pressure, it will "block the path to denuclearization on the Korean peninsula forever -- a result desired by no one."

South Korea has endeavored to maintain the momentum of dialogue in hope that improved inter-Korean ties will facilitate the denuclearization process.

As part of the campaign, it has sought to receive a waiver from US and UN sanctions on Pyongyang for inter-Korean cooperation.

The two Koreas will hold a highly symbolic ceremony to formally start work to modernize and reconnect the cross-border roads and railway tracks at Panmun Station in the North's border town of Kaesong on Wednesday.

The ceremony itself is not subject to the sanctions but South Korea needs prior consultations with the US on the shipment of some materials to be used at the event.

Meanwhile, Lee is to meet with Russian Deputy Foreign Minister Igor Morgulov in Seoul later Tuesday for discussions on the North Korea issue. (Yonhap)