A seven-year-old Beijing girl was confirmed as having H7N9 bird flu yesterday - the first time it has been found beyond Shanghai and neighbouring provinces.
Five other new cases were also reported - one in Shanghai, two in Zhejiang province and two in Jiangsu province - bringing the number of confirmed infections to 49. Of those infected, 11 have died.
All the patients except the one in Beijing were listed as in serious condition.
The new case in Shanghai involves the husband of a woman who died from the virus earlier this month, but authorities stressed there was no evidence of human-to-human transmission.
The seven-year-old girl was in stable condition in Beijing Ditan Hospital in Chaoyang district. Ditan hospital has been assigned to handle infectious disease outbreaks since the severe acute respiratory syndrome outbreak a decade ago.
Beijing health authorities said both the girl's parents were vendors in a poultry market in Shayu town, Shunyi district. The parents have been quarantined and their house sealed and guarded.
Authorities said that people who had been in close contact with the girl had so far shown no signs of the disease.
The girl developed flu symptoms on Thursday morning and was admitted to hospital that night. The health bureau said the girl's condition had improved after doctors gave her the antiviral drug Tamiflu and traditional Chinese herbs.
Beijing municipal authorities said they would strictly implement a ban on the live poultry trade which began in 2005 but has not been widely followed.
Poultry in the infected girl's village will be culled, but authorities said they would not yet carry out a citywide cull.
The man in Shanghai whose wife died of H7N9 was diagnosed with the virus 10 days after her death. The couple's home was close to a poultry farm, Xinhua reported yesterday. It quoted experts as saying there was insufficient evidence to show that the 56-year-old caught H7N9 from his wife.
They suggested the two may have been exposed to the virus at the same source. Shanghai has now reported 21 cases of H7N9 and seven deaths.
The two new cases in Jiangsu involve a 77-year-old woman from Nanjing and a 72-year-old man from Changshu .
The two new cases in Zhejiang involve a 65-year-old retired man and a 38-year-old worker.
In Hong Kong, three people suspected of having H7N9 tested negative, the Centre for Health Protection said.
Dr Ho Pak-leung, president of the University of Hong Kong's Centre of Infection, said the city should consider banning the sale of live chickens in wet markets, as it was only a matter of time before the H7N9 virus reached the city.
However, Chief Secretary Carrie Lam Cheng Yuet-ngor said Hong Kong was focusing on prevention, and it was too early to discuss whether to ban the selling of live chickens.
Additional reporting by Simpson Cheung
Video: Hong Kong tests China poultry for flu
View H7N9 map  in a larger map
Click on each balloon for more information on individual patients infected with the avian flu virus: blue, patients infected with the H7N9 virus under treatment; red, those infected with the H7N9 who have died; yellow, those who have fully recovered; and pink, those with H1N1 avian flu virus.