US Special Representative for North Korea Stephen Biegun on Tuesday wrapped up his three-day visit to Seoul and departed for Japan, with his emphatic call for dialogue with North Korea unanswered.

His high-profile trip focused on efforts to bring Pyongyang back to the negotiating table, as it has been pressuring Washington to make concessions by the end of the year, with hints that it could engage in provocative acts such as a long-range rocket launch.

Appearing at Gimpo International Airport in western Seoul, the US envoy waved away questions from reporters.

His South Korean counterpart Lee Do-hoon rode in the same car with Biegun to the airport in a show of close coordination between the allies on efforts to resume the hitherto unproductive negotiations with the North.

On Monday, Biegun said that the United States has no deadline while stressing the "goal" of fulfilling the commitments that US President Donald Trump and North Korean leader Kim Jong-un made during their first historic summit in Singapore in June last year.

At the summit, the leaders agreed to seek to establish new bilateral ties, make joint efforts to build a lasting and stable peace regime on the peninsula and work toward the complete denuclearization of the peninsula.

Earlier in the day, Biegun gave a closed-door lecture at Yonsei University in Seoul. He was also spotted meeting Kent Harstedt, the Swedish special envoy for Korean Peninsula affairs.

During his stay here, Biegun paid a courtesy call on President Moon Jae-in and held meetings with Unification Minister Kim Yeon-chul, First Vice Foreign Minister Cho Sei-young and his counterpart Lee.

In Japan, Biegun plans to meet the chief Japanese nuclear envoy, Shigeki Takizaki.

The U.S. and the North last held working-level nuclear talks in Sweden in October. The talks ended fruitlessly, with Pyongyang accusing Washington of having come to the negotiating table "empty-handed." (Yonhap)