ULAANBAATAR, Mongolia — Hopes that the rival Koreas would march under one flag as a unified Korean team at a regional judo championship in Mongolia were dashed this weekend by a dispute over the flag.

At the center of the disagreement between the teams competing Sunday at the East Asia Judo Championship in Ulaanbaatar is how the "unification flag" depicts the Korean Peninsula.

The North Korean team opposed the flag because it excluded two islands that are claimed by Japan and administered by South Korea.

North and South Korea have in recent months been cooperating for a series of conciliatory measures. During the Winter Olympics in February, the rival Koreas entered the Pyeongchang Olympic Stadium together, under one flag, which was white with the blue peninsula in the middle.

Kim Jun Ryong, a translator and official for the North Korean judo team, said that there would be no unified team.

"Our team will wrestle under the DPRK flag because of a problem with the flag," Kim said, using the country's official name, the Democratic People's Republic of Korea. "The two islands are not on the flag. The organizing committee tried to make us use a flag without the two islands."

The South Korean judo team expressed hopes that they would be able to compete as a unified team at a later date. Jeon Ki-young, an official with the team, said: "It is impossible to make one team this time, there is politics, it is changing and not this time."

Jeon said he hoped that they could resolve this issue and try again during the judo world championship in September. "We are very excited about this," he said.

During the 2000s, the two countries' athletes marched together at the opening and closing ceremonies of several international sporting events, including the 2000 Sydney Olympics. The last time before February was at the Asian Winter Games in China in 2007.

Mashbat Bukhbat, general secretary of the Mongolian Judo Association, said the North Korean team had initially said they were willing to march under a unified Korean flag.

"However, they said later that they are not ready for this," he added, citing the "global political situation and difficulties."

On Sunday, organizers of the judo championship scrapped team marching altogether.