Japan complained to South Korea about fans waving the Korean peninsula flag at a friendly women's ice hockey match in the Olympics between the combined North and South Korean team and Sweden.
The flag depicts a map of the undivided Korean peninsula, including the disputed islands - known as Dokdo in Korean and Takeshima in Japanese - in the Sea of Japan, known to Koreans as the East Sea.
North Korea's delegation to the Paralympics said on Thursday it "does not accept the fact that Dokdo cannot be marked due to political issues held in Korea", according to the statement from the Korea Paralympic Committee.
North Korean cheerleaders wave unified Korean flags as they cheer during the Women's Ice Hockey Preliminary Round Group B game between Korea and Japan on day five of the PyeongChang 2018 Winter Olympics at Kwandong Hockey Centre
Image credit: Getty Images
In response to the North's claim, the International Paralympics Committee said the two Koreas will march individually as the flag cannot be changed.
The athletes from both Koreas entered together at the opening of the Pyeongchang Olympics on February 9 under the united flag.
The Pyeongchang Paralympics start on Friday and will run until March 18.
North Korea's controversial participation in the Olympics helped ease tensions between the North and the United States, and Japan, over its nuclear and missiles programmes which it conducts in defiance of UN Security Council resolutions and sanctions.
Reclusive North Korea and the rich, democratic South are technically still at war because their 1950-53 conflict ended in a truce, not a peace treaty.