The leaders are slated to meet in Hanoi on February 27-28 to follow up on their first meeting last June in Singapore that ended with vaguely worded commitments on dismantling Pyongyang's nuclear programme.

In the northeastern Chinese city of Dandong, which borders on North Korea, there were signs that Kim's train could be crossing over into China imminently en route to Vietnam.

Guests at a hotel facing the bridge that Kim's train uses to enter China were told by staff to check out on Friday morning.

The Zhonglian Hotel, which is along the Yalu river that separates the two countries, will also be closed on Saturday, staff said.

Sources told AFP that Kim was expected to arrive in Vietnam by train ahead of his planned meeting with Trump and would visit two provinces to take notes on the country's post-war economic development.

"We are preparing for the arrival of the (North Korean) delegation around the 25th of February. We are working on the arrival at Dong Dang railway station, then transfer to Hanoi by car," a source close to logistical preparations told AFP.

Kim is expected to enter Dong Dang en route from Pyongyang, via Beijing, sources and media have said.

A second logistics source confirmed the expected train arrival late on February 25 or February 26.

Kim has previously travelled in an armoured train to Beijing and may stop in the Chinese capital on what could be an epic journey to Vietnam, meeting President Xi Jinping prior to his second face-to-face with the US president.

Or he could save the meeting for his return trip to debrief his country's sole major ally.

In an unprecedented move, Vietnam's Department of Roads also said Friday evening that large trucks would be banned from the road connecting the Dong Dang rail station near the China border to Hanoi on February 25.

A complete ban on all vehicles along the 170-kilometre (105-mile) stretch of road will be in place from 6:00 am to 2:00 pm local time on February 26, implying Kim may arrive that day.

Kim's foreign travel plans are routinely kept secret, with information only made public after his departure from Pyongyang, or upon his arrival home.

Both sources said Kim planned to visit Quang Ninh and Bac Ninh provinces, home to several industrial zones.

Bac Ninh is home to a Samsung factory, a major South Korean investor and leading exporter from Vietnam.

The two logistical sources added that Kim could stay at the Melia hotel in central Hanoi, not far from the Government Guesthouse where the summit is expected to take place.

Meanwhile, a security source at Hanoi's Noi Bai airport said a North Korean delegation had surveyed the site, but that the team had not been instructed to prepare for a "VIP visit" from Pyongyang, suggesting Kim was not expected to travel by plane.

- Armoured train -

Observers hope the much anticipated second summit between Kim and Trump will set deliverable goals after their first meeting failed to offer any real progress on North Korea's denuclearisation.

Kim travelled to the Singapore meeting in a plane on loan from China, but uses a dark green armoured train -- reportedly outfitted with conference rooms and sleeping quarters -- for his trips to close ally Beijing.

Vietnam, a close US ally that maintains ties with Beijing, has been touted as an economic model for isolated North Korea because of its glittering post-war growth that has seen it become one of Asia's fastest growing economies.

burs-dma/rox

MELIA HOTELS INTERNATIONAL SA

SAMSUNG ELECTRONICS