BEIJING -- The A/H1N1 flu outbreak is leading to a potential diplomatic row between China and Mexico, as Chinese health authorities round up and quarantine scores of Mexicans -- only one of whom is thus far reported to be sick -- as they fly in on business and holiday trips.

Mexico's foreign minister said Mexican citizens with no signs of infection had been isolated in "unacceptable conditions" in China. Patricia Espinosa told a news conference Saturday that such measures were "discriminatory and ungrounded" and that the government...