A top North Korean official wrapped up a three-day visit to the United States Saturday after meeting with US President Donald Trump and agreeing to hold a second bilateral summit next month.

Kim Yong-chol, known as a close aide to North Korean leader Kim Jong-un, boarded an Air China flight to Beijing at Dulles International Airport, near Washington, just before 4 p.m. From Beijing, he is expected to return to Pyongyang.

Kim and his entourage refused to answer reporters' questions about Friday's meeting with Trump at the White House or Kim's earlier meeting with US Secretary of State Mike Pompeo.

Both sides were visibly quiet about the envoy's visit, with the State Department confirming the Kim-Pompeo meeting only hours before it took place at the North Korean delegation's hotel Friday morning.

The White House announced after Kim had departed the grounds that he and Trump met for an hour and half to discuss the North's denuclearization and a second summit.

The next summit will happen "near the end of February" at a location to be announced at a later date, it said.

Trump told reporters Saturday that the venue has been chosen but will be disclosed in the future.

Vietnam has been widely reported as the likely site, with both the US and North Korea having embassies there.

The first summit was held in Singapore in June and yielded an agreement to work toward complete denuclearization of the Korean Peninsula in exchange for security guarantees for the North.

The US has maintained that sanctions on the North will remain until it fully and verifiably dismantles its nuclear weapons program, while the North has demanded concessions for the steps it has taken so far, including the dismantling of a nuclear testing site.

Kim was the first North Korean official to fly directly into Washington without a stopover in another US city.

The last senior Pyongyang official to stay in the US capital overnight was the late Vice Marshal Jo Myong-rok, who visited Washington in October 2000 and met with then US President Bill Clinton.

The two countries fought each other in the 1950-53 Korean War, which ended in an armistice, not a peace treaty, and have no diplomatic relations with each other. (Yonhap)