China's financial hub Shanghai reported a human infection of the H7N9 strain of bird flu, local health official said on Monday.

The 37-year-old patient, identified by her surname Chen, was from neighboring Jiangsu Province and diagnosed with the disease on Monday. She has been hospitalized but in critical situation.

Shanghai reported another human infection on Saturday.

The 52-year-old patient, surnamed Wang, is receiving treatment and is in stable condition.

H7N9 is a bird flu strain first reported to have infected humans in March 2013. H7N9 human infections generally peak in winter and spring.