Two Chinese men have died of bird flu in Shanghai after contracting a strain of the disease not previously seen in humans.
Both men, aged 27 and 87, became ill with the H7N9 strain in February and died in March.
A third person — a 35-year-old woman — also caught the virus while in Chuzhou, in the eastern province of Anhui. She is said to be critically ill.
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It is not known how the strain has spread, but the three people who contracted it did not infect each other or anyone else.
All three cases were confirmed by experts from the National Health and Family Planning Commission. They showed symptoms of fever and cough that later developed into pneumonia.
The World Health Organization is "closely monitoring the situation" in China.
"There is apparently no evidence of human-to-human transmission, and transmission of the virus appears to be inefficient, therefore the risk to public health would appear to be low," regional agency spokesman Timothy O'Leary said.
The H7N9 strain of bird flu is thought of as low pathogenic and not easily contracted by humans. The majority of human deaths from bird flu are from H5N1, which killed poultry across Asia in 2003.
There is no vaccine against the H7N9 strain, but the NHFPC is currently testing to assess its ability to infect humans.