Osaka, Japan's harbor city, announced the end of 60-year sister city relations with San Francisco by its mayor on Wednesday, one day after the death of San Francisco's mayor.

The decision, made during Osaka's government meetings on Tuesday, will be officially carried out next June after San Francisco's new mayor takes office, said Osaka Mayor Hirofumi Yoshimura, because "it's not fair to issue an important announcement without the mayor".

The relationship breakdown was ignited by San Francisco's acceptance early this year of a donated memorial of a "comfort woman" - a sex slave in wartime Japan -- according to Yoshimura.

The trust between the two cities has been completely destroyed because of the incident, he added.

San Francisco accepted a "comfort woman" statue in November donated by Chinese-American and Korean-American groups in the United States under the governance of late mayor Edwin M. Lee, the Chinese-American governor of the bay area city, in spite of Yoshimura's opposition on multiple occasions.

The bronze sculpture, standing at St. Mary's Square Park in San Francisco's Chinatown, features three teenage girls of Chinese, Korean and Filipino nationalities holding hands next to an old lady, whose prototype was a wartime "comfort woman" from South Korea. It was the first "comfort woman" statue in a major American city.

Osaka and San Francisco began their sister city relationship in 1957, as they are both harbor cities.