The olive green North Korean train, emblazoned with a yellow stripe, trundling towards Beijing station Tuesday was the first sign leader Kim Jong Un and his entourage had arrived in the Chinese capital.

Unlike that occasion, when the North's state media waited until his return to announce his journey, the official KCNA news agency said Tuesday that he was travelling on board his "private train".

Kim's father and predecessor Kim Jong Il, who is said to have had a fear of flying, stuck to the rails for his own foreign travels, using high-security trains for his seven visits to China and three to Russia over his 1994-2011 term.

According to the official North Korean account, Kim Jong Il was on a train for a "field guidance" visit in 2011 when he died of a heart attack.

The Kims reportedly have several almost identical special trains, made by a factory in Pyongyang.

They are typically composed of two engines and 17 to 21 cars, travel at no more than 60 kilometres per hour, and are said to carry armoured vehicles and small helicopters for emergencies.

The carriages used by Kim Jong Il -- a Macintosh computer on his desk -- and his own father and predecessor, the North's founder Kim Il Sung, are now on display at the Kumsusan Memorial Palace in Pyongyang, where both late leaders' bodies lie in state.

But the current North Korean leader shows no sign of an aversion to taking to the air. Kim flew to Dalian in May and Beijing in June for his second and third meetings with Chinese leader Xi Jinping, and to Singapore -- on board a borrowed Chinese airliner -- for his June summit with US President Donald Trump.

He is also known to travel by air domestically, and was even seen at the controls of an aircraft in video footage released by state media in 2014.

"Our dear Supreme Leader always says it is his profound wish to fly with his soldiers," the announcer says.

(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)