TOKYO, Oct. 2 (Xinhua) -- Japan's Osaka city said Tuesday that it has sent a letter to notify San Francisco of the termination of sister city ties between the two cities in protest of a statue in honor of "comfort women" set up on a public ground in San Francisco.

Osaka Mayor Hirofumi Yoshimura said on Tuesday that the installation of the statue "destroyed the two sides' relationship of trust."

The statue, entitled Women's Column of Strength, was set up by private groups in San Francisco and was later given to the city as a gift.

The late San Francisco mayor Edwin Mah Lee signed a resolution in November last year to accept the gift and turn the statue into a city monument.

Yoshimura, for his part, threatened to scrap the sisterhood between the two cities by the end of that year in protest of the statue, but the decision was delayed as Lee suddenly passed away in December last year.

Osaka city sent a new letter to San Francisco's new mayor London Breed this July to ask about his opinion about the statue, but did not receive a reply by September as it asked.

Yoshimura's decision to cut the sister city ties has drawn much criticism, even when it was a verbal threat and before it was carried out.

"This capricious act by 42-year-old Mayor Hirofumi Yoshimura will not hurt nation brand Korea or nation brand America, but he is hurting city brand Osaka,"said an article on The Japan Times, a well-read newspaper in Japan, in Novemer last year.

"Comfort women is an internet meme as much as a horrible episode in history....It's time for a change in Japan's demeanor regarding its position against the comfort women activism and memorials," the article said.

Women forced into sexual slavery by the Imperial Japanese Army before and during World War II were called "comfort women." The Japanese government has been refusing to acknowledge legal responsibilities for the "comfort women" issue.