GENEVA - China's National Health and Family Planning Commission on Sunday notified the World Health Organization (WHO) of three cases of human infection with H7N9 bird flu in China, the WHO stated Monday.

The WHO's statement said that the cases were confirmed on Friday by Chinese Center for Disease Control and Prevention (CDC). Laboratory testing for influenza A (H3N2), A (H1N1) pdm09 and A (H5N1), as well as for novel coronavirus were negative.

According to WHO, the cases were reported from Shanghai and Anhui province. Respiratory tract infection with progression to severe pneumonia and breathing difficulties has been found in all three cases. Disease onset was between Feb 19 and March 15 2013. The two patients in Shanghai did not survive, and the third one from Anhui is currently in critical condition.

The WHO said there was so far no epidemiological link between the cases that have been identified. Up till now, no further cases have emerged among the 88 identified contacts under follow-up. The source of infection and the mode of transmission are under investigation.

The health organization said the Chinese government was engaged in an active investigation and had instituted enhanced surveillance, laboratory strengthening and training of healthcare professionals for detection, reporting and treatment.

WHO said it was in close contact with the national authorities to follow up the event, and updates would be issued as soon as new information becomes available.