North Korean leader's train arrives in China: Reports

North Korean leader Kim Jong Un's armoured train arrived in China late Saturday ahead of his summit with US President Donald Trump in Vietnam, according to media reports.

The train arrived in the border city of Dandong after 9 pm local time (1300 GMT), according to South Korea's Yonhap news agency and the specialist outlet NK News, though it was not known whether Kim was on the train.

The train's crossing into China follows days of speculation over Kim's travel plans, which remain shrouded in secrecy, as his team gathered in Hanoi ahead of the talks expected next Wednesday and Thursday.

Security was tight before the train's arrival, with police cordoning off the riverfront some 100 metres (yards) from the bridge with tape and metal barriers, and leading an AFP journalist out of the area.

Guests at a hotel facing the rail bridge from North Korea were suddenly asked to leave on Friday and told it was closed Saturday for impromptu renovations.

"The train is long and crossed the bridge slower than the tourist train, but its definitely him, there's a lot of police presence," an unidentified source told NK News.

Windows on the train were blacked out, the source said, with only headlights turned on as it crossed.

Kim has previously travelled in an armoured train to Beijing and, if he is on board, 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.

The Hanoi summit comes after Trump and Kim met in June in Singapore, producing a vaguely worded agreement on denuclearisation, but progress has since stalled, with the two sides disagreeing over what the agreement meant.

Kim travelled to Singapore last year on a plane lent by Beijing, and it remained unclear whether he would ride all the way to Hanoi by rail -- a nearly 4,000-kilometre (2,500-mile) journey taking more than 60 hours from Pyongyang.

Several sources said Kim was expected to arrive in Vietnam by train, stopping at the Dong Dang train station near the China border, then driving on to Hanoi.