Public health authorities in Beijing said on Tuesday that they are keeping a close eye on the H7N9 bird flu virus that has killed two in east China.

Test reagents for the virus have reached the Chinese capital, where the the deadly SARS epidemic played havoc a decade ago, according to a statement from the Beijing Municipal Bureau of Public Health.

The city, with a population of around 20 million, has added avian influenza into its existing monitoring system for regular influenza and pneumonia without a clear cause.

The statement said all hospitals in Beijing have been asked to brace for emergencies and ensure enough medical supplies although no infection has been reported in the city as of Tuesday.

Three infection cases have been reported in east China's Shanghai City and Anhui Province. There are no vaccines against the virus worldwide.