Japan demanded on Wednesday that Pyeongchang 2018 organizers correct a map on its official website which had Japan missing.
The Japan Sports Agency said officials spotted the omission earlier Wednesday, after receiving a number of calls from the public. The agency demanded a correction via the South Korean Embassy in Tokyo, agency official Masahide Katsumata said.
Katsumata said Japan was omitted from the map early Wednesday when he checked it.
The world map on the "Dream Program" section of the website for the 2018 Winter Olympics has since been corrected.
An official from Pyeongchang organizing committee said Japan's omission was a "simple mistake" caused by changes in image files when organizers updated the Olympic website in February.
"We'll keep watching," Japan's Chief Cabinet Secretary Yoshihide Suga said.
The two countries have had past disputes over Japan's wartime aggression and territorial issues.
Japan wants South Korea to stop using "East Sea" for the waters between the two countries, which Tokyo says should be "Japan Sea." The two countries dispute ownership of a cluster of islands, controlled by South Korea but also claimed by Japan under a different name.
The Korean names are still on another map on the Pyeongchang 2018 website. Suga called it "extremely inappropriate" and said Japan will keep protesting.