Chinese cities have stepped up control of the live poultry trade as the number of human H7N9 bird flu infections continues to rise.

Health authorities in Shenzhen, Guangdong province, reported on Sunday a new human H7N9 infection. A 44-year-old man was still in a critical condition at a hospital.

Guangdong province also reported two new H7N9 infections on Saturday. A 4-year-old girl from Guangzhou is in a stable condition. The other patient, a 79-year-old man, also of Guangzhou, is said to be critically ill.