Thirty-nine Japanese suffered food poisoning after dining at the Tokyo American Club in Minato Ward, Tokyo, on Jan. 11, the Tokyo Metropolitan Government said Wednesday.
The victims complained of light food poisoning symptoms after attending an alumni gathering of a Tokyo university at the club.
No one was hospitalized, metropolitan officials said.
As punishment, the ward will order the restaurant in the club to suspend operations.
According to the Tokyo Bureau of Public Health, 163 people attended the gathering. A few participants complained of nausea and other symptoms the following day.
As of Tuesday, 39 cases had been confirmed -- 22 in Tokyo, seven in Kanagawa Prefecture, six in Chiba Prefecture, two in Saitama Prefecture and one each in Tochigi and Gunma prefectures. The number of victims is expected to increase.
The Tokyo American Club is a membership club catering to Americans in Japan, but is also open to Japanese.