HONG KONG, Jan. 31 (Xinhua) -- Ocean Park, one of Hong Kong's favorite tourism attractions, announced here Thursday to shut down its walk-through aviaries for 21 days after a dead bird found in the park was suspected of infecting H5 bird flu virus.

    The carcass of black-crowned night heron was collected on Monday near the Ocean Park's popular attraction, a spokeswoman for the park said, adding that it's necessary for the park to take precautionary measures.

    The spokeswoman said the dead bird, found in a remote, non-guest area, was not among the collections of the aviaries and she believed it came from the wild.

    The Agriculture, Fisheries and Conservation Department confirmed late Wednesday night that the dead bird was suspected of infecting with the H5 avian influenza virus after preliminary testing.

    A spokesman for the department said further confirmatory tests were being conducted on the black-crowned night heron, a common resident and winter visitor to Hong Kong, stressing the department will closely monitor the situation.

    Since 2005, fecal samples of the birds kept by the Ocean Park have been submitted to the Agriculture, Fisheries and Conservation for H5 testing as part of the overall avian influenza surveillance program. All samples collected from the Park have tested negative so far.

    The spokesman said that the department would conduct frequent inspections of poultry farms and the wholesale market to ensure that proper precautions against avian influenza had been implemented.

    "The threat of avian influenza remained," the department's spokesman said, adding "the relevant departments will remain vigilant and continue to take preventive and control measures against avian influenza."