An elderly man has died of bird flu in Hong Kong in the city's first human case of the disease this winter, authorities said Tuesday.

The 75-year-old was diagnosed following a visit to neighbouring Guangdong province in mainland China, where he bought a chicken from a market.

He died on Sunday after testing positive for the H7N9 strain of bird flu, health officials said.

More than 50 people who had close contact with the victim, including people who lived with him and health care staff, were placed under medical surveillance, the South China Morning Post reported on its website.

The paper said it was the 17th imported case of H7N9 to be confirmed in Hong Kong, a semi-autonomous southern Chinese city.