A group of officials, including Ryu Myong-son, department director of the Central Committee of the ruling Workers' Party of Korea, and Kim Nung-o, head of the party's North Pyongan Central Committee, were seen visiting Beijing, according to the sources.

China's foreign ministry refused to confirm the visit by the North Korean officials.

"As for the exchanges between North Korea and China, there has been normal contact between the two sides," ministry spokesperson Lu Kang said in response to a question posed by Yonhap News Agency.

"There is nothing concrete that I know about the visit," he added.

The Pyongyang officials arrived at a Beijing airport earlier in the day and got into vehicles prepared for them by China before leaving for the Diaoyutai State Guesthouse. The airport was said to have been blocked when they arrived.

About seven or eight vehicles, including ones with North Korean flags, were later spotted entering the east gate of the guesthouse.

Details of their trip and schedule have not been released.

The trip might be aimed at discussing follow-up measures to what was agreed during the summit talks held last week between North Korean Kim Jong-un and Chinese President Xi. It also comes after a meeting between Kim and U.S. Secretary of State Mike Pompeo in Pyongyang.

Currently, North Korea and the US are preparing to hold an unprecedented summit scheduled for June 12 in Singapore. Denuclearization of the North is likely to top the agenda.

A source said that given the possible nature and purpose of the visit, it is likely that Kim Yong-chol, a vice chairman of the central committee of the WPK and head of the North's United Front Department handling inter-Korean relations, could be in the delegation. (Yonhap)