Two people have died in Shanghai, one of China's largest cities, after contracting a strain of avian influenza that had never been passed to humans before, the official Xinhua news agency reported.
The two men, aged 27 and 87, became sick late February and died in early March, Xinhua said on Sunday.
Another woman in nearby Anhui province also contracted the virus in early March and is in a critical condition, Xinhua said, quoting the National Health and Family Planning Commission (NHFPC).
Rate of infection
The strain of the bird flu virus found in all three people was identified as H7N9, which had not been transmitted to humans before, the commission said.
The three cases were confirmed to be human infection of the H7N9 strain by experts from the NHFPC, based on clinical observation, laboratory tests and epidemiological surveys, Xinhua said.
All three cases showed symptoms of fever and coughs that later developed into pneumonia.
Calls to the NHFPC on Sunday were not answered.
It is unclear how the three victims were infected. The virus does not seem highly contagious because no health abnormalities were detected among 88 of the victims' close contacts, Xinhua quoted the commission as saying.
There are no known vaccines against the H7N9 virus.