Mexico's government on Sunday called China's treatment of its citizens unacceptable and said it would not participate in a Shanghai trade fair in a dispute over anti-swine flu measures adopted by the Asian giant. Already angered by China's quarantining of dozens of Mexican travelers, flight cancellations and a ban on its pork imports, Mexican officials said China had withdrawn Mexico's "guest of honor" status at the May 19-21 food fair. It was part of a wider series of snubs by many nations that has left Mexico - once the epicenter of the swine flu epidemic, but now surpassed in total cases by the United States - feeling unfairly singled out. "The recently adopted measures by fair organizers and the Chinese government are unacceptable," said a statement from ProMexico, the government's agency that promotes foreign trade. Thirty Mexican companies had planned to participate.