In east China's Zhejiang province, a human case of H7N9 was reported, said health authorities.
The patient is a 34-year-old woman surnamed Cai, who is from the city of Zhuji. She was confirmed to be infected with the bird flu virus Saturday, Xinhua quoted the provincial health and family planning commission as saying.
By 1 p.m. Sunday, she was still in critical condition at a local hospital, the statement said.
This is the first case to be reported in Zhejiang this year. In November, two cases were reported in the province.
It is the second case to be reported in China this year.