Seoul confirmed on Wednesday that the high-level North Korean official who visited China from Sunday was leader Kim Jong-un. 

North Korea also confirmed that Kim made an unofficial visit to China from Sunday to Wednesday at the invitation of Chinese President Xi Jinping. 

Kim crossed the Sinuiju-Dandong border on a special train on Sunday and arrived in Beijing on Monday. He left the Chinese capital Tuesday afternoon. 

A senior presidential official said Kim's train returned to North Korean territory Wednesday morning.