South Korea denounced Japan for its repeated territorial claims to Dokdo islets, called Takeshima in Japan, lying halfway between the two countries.

A joint press conference in Washington between the deputy foreign ministers of Japan and South Korea was canceled at the last minute because of "differences" between the two US allies, US Deputy Secretary of State Wendy Sherman, who had been due to host the event, said on Wednesday.

"As has been the case for some time, there are some bilateral differences between Japan and the Republic of Korea that are continuing to be resolved," Sherman said. 

"And one of those differences which is unrelated to today's meeting, has led to the change in format for today's press availability," she said, standing alone on the podium where she had been scheduled to be joined by Choi Jong-kun of South Korea and Mori Takeo of Japan. 

She did not give any details on what that "difference" entailed.

But Japan did say why it objected to the press conference: It said that on Tuesday the commissioner-general of South Korea's National Police Agency visited islets that are claimed by Japan and administered by South Korea.

Japan calls them Takeshima and says they are part of its Shimane Prefecture. South Korea calls them Dokdo.

This was the first time in 12 years that a commissioner-general of the National Police Agency landed on the islets, the Asahi Shimbun newspaper reported.

A Japanese Embassy spokesperson in Washington said the islets are "indisputably an inherent part of the territory of Japan" and that Japan lodged a protest with South Korea over the visit by the police official.

"Under these circumstances, we have decided that it is inappropriate to hold a joint press conference," the spokesperson said.

The trilateral meeting between diplomats from the three allies did take place, behind closed doors. 

Sherman said the talks had been "very constructive," which, she noted, "demonstrates exactly why the trilateral format with the United States, Japan, and the Republic of Korea is so important and powerful."

Tokyo and Seoul have had strained relations for decades due to Japan's brutal colonial rule over the Korean Peninsula between 1910 and 1945. 

AFP