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.

There have been more than 120 human H7N9 cases reported in China this year, and at least 32 deaths, according to the health ministry's official tally last week.

The poultry trade has been identified as a primary source of human infection for the virus, as most of the patients had close contact with poultry.

On Saturday, Guangzhou, banned all live poultry markets for two weeks. The ban remains in effect through Feb 28 as part of the government's new effort to curb the spread of the H7N9 virus.

Hangzhou, Zhejiang province, announced on Saturday it would permanently stop the live poultry trade in the city proper. A temporary ban had already been in place since Jan 24, a week before Spring Festival.