He arrived at 4:00 pm at Beijing Railway Station and was greeted by Cai Qi, China's number five-ranked official, and Foreign Minister Wang Yi, KCNA reported.

Earlier on Tuesday, AFP journalists saw a train flying North Korea flags and believed to be carrying Kim approaching the station.

Kim will join Chinese President Xi Jinping, Russia's Vladimir Putin and two dozen other leaders at the huge spectacle to mark 80 years since the end of World War II.

China will showcase its military prowess with troops marching in formation, flypasts and other high-tech fighting gear at the showpiece extravaganza centred on Beijing's Tiananmen Square.

South Korea's Yonhap news agency also reported the special armoured train's arrival in the capital.

Kim appeared to be accompanied by his daughter Kim Ju Ae, South Korea's National Intelligence Service said in a statement to reporters.

It is only Kim's second reported trip abroad in six years and first to China since 2019.

China has touted the parade as a show of unity with other countries, and Kim's attendance will be the first time he is seen with Xi and Putin at the same event.

Photos released by KCNA showed Kim smoking a cigarette outside his olive-green train with Foreign Minister Choe Son Hui and close aide Jo Yong Won.

Another pictured Kim grinning inside his lavish, wood-lined train carriage in front of a North Korean flag and national emblem.

Both images were taken on Monday, according to KCNA.

Kim's appearance in China "formalises the China-Russia-North Korea trilateral (relationship) to the public", Soo Kim, a geopolitical risk consultant and former CIA analyst, told AFP.

Kim enjoyed a brief bout of high-profile international diplomacy from around 2018, meeting US President Donald Trump and then South Korean president Moon Jae-in multiple times.

But he withdrew from the global scene after the collapse of a summit with Trump in Hanoi, Vietnam, in 2019.

Kim stayed in North Korea throughout the Covid-19 pandemic, but met Putin in Russia's far east in 2023.

- Flags, flowers and fanfare -

Security around Beijing has tightened in recent days and weeks, with road closures, military personnel stationed on bridges and street corners, and miles upon miles of white barriers lining the capital's wide boulevards.

Art installations with flowers, doves and an emblem showing the Great Wall of China with "1945-2025" have cropped up around the city, and on Tuesday Chinese flags flew in residential neighbourhoods.

Officials have been tight-lipped over the list of hardware to be displayed at the parade, but military enthusiasts have already spotted significant new systems, including what is rumoured to be a gigantic laser weapon.

Millions of Chinese people were killed during a prolonged war with imperial Japan in the 1930s and 40s, which became part of a global conflict following Tokyo's attack on Pearl Harbor in 1941.

Wednesday's event caps a bumper week of diplomacy for President Xi, who on Sunday and Monday hosted a slew of Eurasian leaders for a summit in the northern port city of Tianjin aimed at putting China front and centre of regional relations.

The club of 10 countries -- named the Shanghai Cooperation Organisation (SCO) -- touts itself as a non-Western style of collaboration in the region and seeks to be an alternative to traditional alliances.

During the summit, Xi slammed "bullying behaviour" from certain countries -- a veiled reference to the United States -- while Putin defended Russia's Ukraine offensive, blaming the West for triggering the conflict.

Many of the guests from the Tianjin gathering, including Putin, Belarusian President Alexander Lukashenko and several other leaders will join Xi and Kim for the parade in Beijing.