Two more human cases of H7N9 avian flu were reported in south China's Guangdong Province, local health authorities said Sunday.

The two patients, a 62-year-old man from Dongguan City and a 78-year-old woman from Shanwei City, were confirmed infected on Saturday and are in a critical condition, the provincial health and family planning commission said in a statement.

At least 17 human cases have been reported in the province this month.

H7N9 is a bird flu strain first reported to have infected humans in March 2013, killing three in east China. With symptoms including fever, cough and respiratory failure, it has repeatedly cropped up in winter and spring seasons.

In addition to Guangdong, Shanghai, Fujian and Zhejiang along the eastern Chinese coast have all reported human cases of H7N9 this winter.