China has confirmed 77 human cases of H7N9 avian influenza since announcing two weeks ago that it had found the strain in people for the first time.
The new strain of the flu had been confined to the eastern city of Shanghai and nearby Zhejiang, Jiangsu and Anhui until Saturday when the first case was reported in Beijing.
It has since spread west to the central province of Henan where two new cases were reported on Sunday.
China confirmed 14 new H7N9 cases between 6 pm on Monday and 8 pm Tuesday, Xinhua said, with two more deaths reported in Shanghai.
A total of 30 cases, including 11 ending in death, have now been reported in Shanghai, said Xinhua.
Eight of the people reported on Tuesday to have contracted H7N9 bird flu were said to be in critical condition.
Three of these were in Jiangsu, according to Xinhua, which cited the province's health department. They are a 21-year-old woman, and two men aged 56 and 72.
The other five were in Zhejiang, where three men and two women aged between 56 and 72 tested positive for the virus.
As of Tuesday, Zhejiang has confirmed 21 H7N9 cases, including two that have ended in death.
A seven-year-old girl in Beijing who tested positive for H7N9 in the capital's only reported case so far will be discharged from hospital on Wednesday, Xinhua said.
She has been treated for the past six days and is now testing negative for the virus.
A four-year-old boy who had tested positive was discharged from a Shanghai hospital last Wednesday, said Xinhua citing local health authorities.
He has been the only confirmed case to make a full recovery.
Health authorities in China say they do not know exactly how the virus is spreading, but it is believed to be crossing from birds to humans, prompting mass culls in several cities.
Experts fear the prospect of the virus mutating into a form easily transmissible between humans, which would have the potential to trigger a pandemic -- but the World Health Organization (WHO) has said there is no evidence yet of such a development.
International experts are preparing to head to China to probe the outbreak, the WHO said on Tuesday.
The mission, including four international flu specialists, is due to arrive in the coming days for a week-long investigation.
Taiwan announced on Tuesday that it is planning a permanent ban on the killing of live poultry in traditional markets amid concerns over the spread of the H7N9 avian flu virus in China.
Chinese state media on Monday urged people to keep eating chicken and help revive the poultry industry, which lost 10 billion yuan ($1.6 billion) in the week after the virus began infecting humans.