North Korean leader Kim Jong-un has made a surprise visit to China, according to reports, which described a special North Korean-style green train arriving in Beijing amid heavy security.

Japanese media described the train as green with yellow horizontal lines and 21 carriages – similar in style to the train that carried Kim’s late father, Kim Jong-il, when he visited China in 2011. Train delays of up to two hours were reported by the Beijing railway bureau.

The visit to China would be Kim’s first known trip overseas since he took power in 2011 and comes ahead of the much-hyped talks with US President Donald Trump.

Intriguing images from Beijing, captured by Japan's Nippon TV. A 21-car train, similar to one used by Kim Jong Il in 2011, pulled into Beijing Station around 3pm. Met by honor guard and line of VIP cars. Speculation is that Kim Jong Un could be in Beijing. https://t.co/OR40pYEcgGpic.twitter.com/1G5jndciIr — Martyn Williams (@martyn_williams) March 26, 2018

Details of Kim’s trip, including how long he will stay and who he plans to meet, were not immediately available, according to three sources who spoke to Bloomberg News.

Responding to questions about the visit, China’s foreign ministry said it was “not aware of the situation”. It was also unclear whether the US had advance knowledge of the trip.

Reports of a long motorcade with a police escort making its way down Beijing’s Changan Avenue, in the direction of the Diaoyutai State Guest House, have added to speculation that North Korea’s leader was in the city.

Alleged footage of North Korean dictator Kim Jong Un's motorcade in Beijing, China. pic.twitter.com/xpNXa4OSen — Josh Caplan (@joshdcaplan) March 26, 2018

Kim previously agreed to meet South Korean president Moon Jae-in in April, following diplomatic talks in February.

Relations between Beijing and Pyongyang have been strained, as China has backed UN sanctions on North Korea as Kim pursues his nuclear weapons program. China opposes Pyongyang’s nuclear ambitions but is also wary of any instability that would result in the region if Kim’s regime collapsed or if a war broke out on the Korean Peninsula.

Earlier this month, Trump agreed to a meeting with Kim if the North Korean leader makes certain commitments regarding its nuclear program before any meeting takes place.

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