Admitted to Tuen Mun hospital on Tuesday after developing a fever, the Hong Kong citizen was diagnosed on Friday with bird flu. His case comes after an Indonesian domestic helper was on Monday found to have been infected with the disease.

She remains in a critical condition, while the 80-year-old man - who had been living in the neighboring mainland Chinese city of Shenzhen - is listed as stable.

"Tonight we have confirmed the second human case of avian flu influenza A H7N9. We believe this is an imported case," Hong Kong Center for Health Protection controller Leung Ting-hung told reporters on Saturday.

"We are still investigating if the patient had exposure to poultry, but he definitely did not in Hong Kong.

"There is no evidence that this virus can cause sustained human-to-human transmission so the risk of widespread or community-wide outbreak is low," Leung said.

Tests negative

News agency AFP reported that of those quarantined, 18 have tested negative to the virus, with the results of one patient pending. Relatives, other patients from the 80-year-old sufferer's hospital cubicle and a taxi driver are all among those who will stay in quarantine for a period of 10 days after coming into contact with the man.

The government had already quarantined 17 other people who had been in close contact with the 36-year-old Indonesian patient.

"She has a history of traveling to Shenzhen, buying a chicken, slaughtering and eating the chicken," Hong Kong health minister Ko Wing-man had said of woman.

The two cases are not believed to be linked, but they have put Hong Kong on alert. Almost 300 people died when an outbreak of Severe Acute Respiratory Syndrome, otherwise known as SARS, hit Hong Kong in 2003.

Health authorities are wary of the H7N9 bird flu virus spreading beyond mainland China. Border checks were stepped up since the Indonesian woman was diagnosed. The World Health Organization puts China's reported death toll from the virus at 45 since February.

ph/se (AFP, AP, Reuters)