Concern has mounted in Hong Kong as neighboring Dongguan city in Guangdong started culling poultry after suspected H7N9 bird flu was detected in chicken for the first time.
In Beijing, Premier Li Keqiang visited a disease control center to stress the importance of preventive efforts.
The mainland reported 11 more people with H7N9 bird flu, bringing the total number of infections to date to 123, including 24 deaths.
The central province of Hunan confirmed its first case yesterday, while eastern Jiangxi reported three more for a total of five, and Fujian recorded its second case.
Li asked medics to stay on high alert as "this is a new virus, and we don't have all the information."
He added: "It looks preventable and controllable now, and there is no evidence showing human-to- human transmission."
In Dongguan, about 90 kilometers from Hong Kong, 130 samples were collected from a wholesale market and one sample tested positive for H7 - of which H7N9 is a subgroup. City officials ordered the closure and sterilization of poultry markets.
Other areas in Guangdong have also stepped up inspections and virus tests in poultry markets.
No human infection of the virus has been found in the province so far.
Secretary for Food and Health Ko Wing-man said the "chicken sample showing positive toward the H7N9 virus has been sent to the Chinese Center for Disease Control and Prevention, and results are expected to be out within a few days."
Hong Kong has no plans to stop importing poultry from the mainland, he said, as no farms in the 13km perimeter of the affected market supplies chickens to the territory. But Ko said authorities are ready to halt imports or cull birds if necessary.
Cases in the past week in the southern provinces of Hunan, Jiangxi and Fujian - which all border Guangdong - suggest that the virus might surface in Guangdong, he said.
Meanwhile, ahead of the May 1 Golden Week, Secretary for Commerce and Economic Development Gregory So Kam-leung said hotels in Hong Kong are prepared for the situation.
"Guidelines have been issued to hotels and travel agencies, reminding them to pay attention to the health of guests during the holiday," he said.