The top nuclear envoys of South Korea, the United States and Japan held a breakfast meeting to discuss the implementation of international and bilateral sanctions on North Korea and the possibility of its additional provocations, a foreign ministry official said Wednesday.

Kim Hong-kyun, South Korea's special representative for Korean Peninsula peace and security affairs, held the unofficial meeting with his U.S. and Japanese counterparts Sung Kim and Kimihiro Ishikane.

Their gathering came the day after their vice foreign ministers held a trilateral meeting to strengthen cooperation to deter Pyongyang's future provocations and further pressure the wayward regime to renounce its nuclear ambitions.

The series of diplomatic consultations among the three nations came as the North is seen preparing for a fifth nuclear test despite international warnings against it.

Recent satellite imagery has indicated a sharp increase in the movement of workers, vehicles and equipment at the Punggye-ri nuclear test site in the country's northwest, reinforcing concerns over another nuclear test, which experts say would bring the country closer to its goal of becoming a nuclear-weapon state.

The nuclear envoys of South Korea and the U.S. are expected to hold a dinner meeting to further discuss bilateral and multilateral cooperation to strengthen pressure on Pyongyang through beefed-up sanctions and other methods. (Yonhap)