China on Monday confirmed its first case of swine flu on the mainland in a Chinese man who recently travelled back from the United States, the Xinhua news agency reported.
The 30-year-old man surnamed Bao was hospitalised with a fever after arriving in the city of Chengdu in southwestern China from the United States via Tokyo on Saturday afternoon, Xinhua said, citing the Ministry of Health.
Bao had travelled to Beijing on Northwest Airlines flight NW029 from Tokyo before connecting to Chengdu, it said.
The man was transferred to an infectious diseases hospital in Chengdu, and people who came into close contact with him during his medical examination had been placed under observation, Xinhua said.
More than 130 of the 150 passengers aboard the same Northwest flight have also been tracked down and put into quarantine, Xinhua said, quoting Chengdu officials.
The government was "stepping up efforts to search and trace" any remaining people who may have come into close contact with Bao, the officials said.
Asia's first case of swine flu was reported in Hong Kong on May 1, when a Mexican national tested positive for A(H1N1) after flying into the semi-autonomous southern Chinese city from Mexico via Shanghai.
The case led to scores of people being placed in quarantine in China, Taiwan and Hong Kong, including the Mexican's fellow airline passengers and almost 300 guests and staff at the Hong Kong hotel where he had checked in.
China has defended its strict swine flu prevention measures, saying they were necessary to stop the virus spreading through Asia and to avoid "catastrophic consequences" in the world's most populous nation.