A thirty-year old man returning to Chengdu from studying in the United States is the first suspected case of H1N1 flu – aka swine flu – on the Chinese mainland, according to a statement by China's Health Ministry yesterday.

The man is currently under quarantine in a Chengdu hospital where he is receiving treatment.

"According to clinical appearances and the results of laboratory tests, the initial diagnosis is that it is a suspected case of type A H1N1 flu," the Health Ministry statement said.

Chinese health authorities are urgently seeking the man's fellow passengers on Northwest Airlines flight NW029 from Tokyo to Beijing at 1:30 am on Saturday or Sichuan Airlines flight U8882 from Beijing to Chengdu at 10:50 am on Saturday.