A man who died last week in the south Chinese province of Guangdong has been confirmed by the health ministry as the country's ninth victim of bird flu.
Hong Kong says it may have to tighten its border controls
The 32-year-old fell ill after frequenting a market in the main city, Guangzhou, and he was diagnosed as having the H5N1 strain of the virus.
The victim had also spent time near a site where poultry was slaughtered.
Hong Kong, which neighbours the province, has warned that the risk of a human case there has increased.
Named only as Lao, the new victim brings to 15 the number of human cases registered officially on the Chinese mainland.
According to World Health Organisation (WHO) figures, as of 1 March, bird flu had killed 94 people in Asia and the Middle East since its appearance in late 2003.
Scientists fear the virus could mutate to spread between humans, triggering a global pandemic.
Apart from the nine deaths, two people are still being treated for the virus in China while four have been released from hospital, the country's state news agency Xinhua reports.
It said that the diagnosis of H5N1 had been made in accordance with both Chinese and WHO standards.
People who had been in close contact with Lao have been put under medical observation by the health authorities in Guangdong though no symptoms have been detected to date.
Hong Kong's director of health, Lam ping-yan, said this weekend the risk of human infection from bird flu had grown in the territory, which has escaped the virus so far.
He said officials might have to ask travellers using border checkpoints from the mainland to declare their health condition.