Embattled Osaka Mayor and Nippon Ishin no Kai (Japan Restoration Party) coleader Toru Hashimoto faced fresh criticism Tuesday from the San Francisco mayor's office over his remarks about the necessity of Japan's wartime brothels.

Osaka says Hashimoto will meet with San Francisco Mayor Edwin Lee on the morning of June 11, but the international firestorm created by the Nippon Ishin leader's remarks that Japan's "comfort women" system had been necessary at the time has infuriated human rights groups and the U.S. State Department, which called Hashimoto's remarks outrageous and offensive.

That view is shared by the San Francisco mayor, and despite the schedule Osaka announced, Lee's office says the Hashimoto meeting has not been confirmed.

"Mayor Lee is disappointed and offended by (Hashimoto's) statement," said Francis Tsang, a spokesman for the mayor.

In addition, San Francisco's Department of the Status of Women, formed in 1998 by the city, has criticized Hashimoto's comments.

"Sex slavery is never 'necessary,' " Emily Murase, the department's executive director, said in a statement. "To justify the exploitation and suffering experienced by the women, some just girls, who were forced into prostitution by the Japanese military during World War II is a flagrant denial of human rights."

Osaka and San Francisco have a sister-city relationship dating back to 1957, and mayoral delegations have visited each other on numerous occasions over the years. The San Francisco-Osaka Association condemned Hashimoto's remarks last week.

"Statements that justify controversial wartime abuses and devastating violence against women are damaging to international relations and contrary to the mission of the association," it said.