BEIJING/SEOUL -- A high-ranking North Korean official, possibly even leader Kim Jong Un, arrived in the Chinese capital aboard a special diplomatic train Monday, multiple sources familiar with bilateral relations told Nikkei.
Unconfirmed accounts suggest that a train traveled from North Korea to Beijing via Dandong, a Chinese border city that sits across the Yalu River from North Korea.
The dignitary aboard the train is reported to have been transported to the Diaoyutai State Guesthouse in a convoy of cars. A video of dozens of cars travelling on the main streets of Beijing and entering Diaoyutai was uploaded to the internet on Monday. On Tuesday morning a convoy left the State Guesthouse.
Security was tight Monday around the Great Hall of the People, where Chinese leaders usually host visiting heads of state. The heavy police presence, including vehicles belonging to the special police unit, is the sort of response seen when a head of state is in town, according to local residents.
The lack of flags on display that typically greet foreign leaders suggests that the visit is unofficial. This has fueled speculation that the mystery guest is Kim Jong Un himself or Kim Yo Jong, his younger sister, who led the North Korean delegation to last month's Winter Olympics.
If Kim Jong Un is one of the visitors, that would make it the first-ever foreign trip by the North Korean leader since he took over his father's spot in 2012.
However, there has been no official confirmation. Bloomberg, citing three unidentified sources, reported on Monday that Kim Jong Un was in Beijing. South Korea's Yonhap news cited a government source who said, "There is not enough circumstantial evidence to indicate that Kim Jong Un is visiting China, although the possibility cannot be ruled out."
White House spokesman Rah Shah said Monday the U.S. could not confirm reports that he was in China.
Hua Chunying, the Chinese Foreign Ministry spokeswoman, told reporters Monday that she was unaware whether a high-ranking official from North Korea had arrived in Dandong over the weekend.
Masayuki Yuda, Nikkei staff writer in Tokyo, contributed to this report.