The girl, surnamed Peng, was found ill on Jan 7 in central Hunan Province and was taken to hospital in Luliang City of Shanxi on Jan 11, Xinhua said, citing an unnamed official with the Shanxi provincial health department.

The girl had tested positive for the H5N1 strain of avian influenza and 'was in critical condition', Xinhua cited the official as saying.

'All people who have had close contact with her are under strict medical observation ... Up to now, no abnormal symptoms have been found,' a statement on China's Health Ministry website said.

The Health Ministry had notified the World Health Organization, authorities in Hong Kong and Macau, and some other countries, the statement said.

China confirmed earlier this month a woman infected with bird flu had died in Beijing after buying nine ducks at a market in Hebei province, which surrounds the Chinese capital, sparking emergency checks of local poultry markets.

The H5N1 remains largely a disease among birds but experts fear it could change into a form that is easily transmitted from person to person, and spark a pandemic that can kill millions of people worldwide.

At least 21 people have died of bird flu out of 32 people infected in China. -- REUTERS