North Korea's envoy for the United States arrived in Beijing on Tuesday apparently on his way to Hanoi for talks on the agenda of an upcoming summit between leader Kim Jong-un and US President Donald Trump.

Kim Hyok-chol, special representative for US affairs of the State Affairs Commission, is expected to visit the Vietnamese capital to meet with his American counterpart, Stephen Biegun, to nail down the details of what will be discussed in the second meeting between Trump and Kim in Hanoi on Feb. 27-28.

Alex Wong, US deputy assistant secretary of state for North Korea, also headed to Hanoi, and Biegun plans to depart from Washington, D.C. later this week, a diplomatic source said.

Wong was a member of the US delegation, led by Biegun, to Pyongyang early this month.

Shortly after Biegun's negotiations with Kim Hyok-chol at that time, Trump announced that Hanoi would host his talks with the North's leader.

Another team of senior North Korean officials, headed by Kim Chang-son, is on a visit to Hanoi as well to check and discuss protocol and logistical issues.

Kim, chief secretary of North Korea's State Affairs Commission, is known as the de facto chief of staff to the communist nation's leader.

He was in charge of the affairs for the Singapore summit in June last year between the leaders of the two sides. (Yonhap)