WASHINGTON - The mayor of New Orleans, Ray Nagin, was being held Sunday in a hotel in Shanghai, after a fellow passenger on his flight to China fell ill with a suspected case of swine flu, US media reported.

Nagin, his wife, Seletha, as well as a member of his staff were on a 10-day trip to China and Australia aimed at promoting business to his city, the New Orleans Times Picaynune newspaper reported.

A spokeswoman for the southern US city told the daily that the trio, who were quarantined as a precaution, had been seated during their flight near a passenger who showed "signs and symptoms of an influenza-like illness suspected to be of the H1N1 subtype".

City communications director Ceeon Quiett told the daily that Nagin, his wife and aide are "symptom-free" and "being treated with utmost courtesy by Chinese officials", but said there was no word on how long the quarantine would last.