Two more cases of H7N9 bird flu virus have been detected in Zhejiang province, including a man who died last week, authorities said on Wednesday.

The Chinese Center for Disease Control and Prevention confirmed that a 38-year-old patient surnamed Hong from Hangzhou, the provincial capital, who died in hospital on March 27, had the virus.

Hong was infected on March 7 while working in neighboring Jiangsu province. He returned home on March 18, according to the Zhejiang health department.

The other patient, surnamed Yang, is a 67-year-old man. He developed a cough and fever on March 25 and was admitted to hospital on Tuesday.

None of the people who came into close contact with the patients have developed symptoms of the flu, the health department said.

On Sunday, two men in Shanghai died from H7N9. A woman in Anhui province and four men in Jiangsu province remain in critical condition.

All patients had fevers and coughs in the early stages before developing pneumonia and breathing difficulties, China's health authorities said.

Experts say genetic analysis shows the H7N9 virus can be treated with Tamiflu, an antiviral drug that may slow the spread of influenza in the body.

Wang Xianjun, head of the Shandong provincial center of disease control, said H7N9 is sensitive to neuraminidase-inhibiting medicine such as Tamiflu, Qilu Evening News reported on Wednesday.

There are no effective vaccines for H7N9 as yet, Wang said, but using Tamiflu may be effective in the early stages.