An 81-year-old man died of H7N9 avian flu infection on Thursday in east China's Fujian Province, according to a statement released by the provincial health authorities on Friday.

To date, Fujian has reported 15 human cases of H7N9 infection, said the statement released by the health and family planning commission of Fujian.

On Friday, the eastern province of Zhejiang also reported four more new cases of the disease, bringing the number of H7N9 human cases in the province to 73 in 2014, said the provincial health authorities.

Among the four new cases, one female patient in Taizhou City was in critical condition and three male patients in the provincial capital of Hangzhou were in serious condition.

Central China's Hunan Province on Friday reported one new case of H7N9 infection in a 21-year-old woman, and a discharged case involving an 8-year-old girl who recovered after medical treatment.

China has so far reported more than 120 human H7N9 cases this year, including over 25 deaths, with Zhejiang and Guangdong being most affected.

The National Health and Family Planning Commission on Wednesday reaffirmed that no proof has been found that the H7N9 virus is spreading from human to human, adding that most human H7N9 infection cases have been isolated.

Expert teams sent by the commission have been supervising local hospitals in Beijing, Shanghai, Zhejiang, Fujian and Guangdong in diagnosing and treating H7N9 patients, according to the commission.