On Monday, Japan’s Kyodo news agency reported that a "special" train from North Korea crossed the Chinese border near the city of Dandong the day before, sparking speculations that Kim was on board. South Korean media reported that Kim had met with a number of Chinese officials, including President Xi Jinping.
"Kim Jong Un really visited China," a source in the South Korean intelligence told The Chosun Ilbo newspaper.
However, South Korea has not made any official statements on the issue yet.
If the North Korean leader was indeed on board the train, this would have been his first trip abroad since coming to power in 2011. The news comes ahead of Kim’s planned summits with South Korean leader Moon Jae-in in late April and US President Donald Trump in May.