TOKYO, Jan. 31 (Xinhua) -- Japan's agriculture ministry confirmed Wednesday that bird flu at a poultry farm in southern Japan was the deadly H5N1 strain, after several similar cases were reported within the month.

    Some 12,000 birds at the farm in Okayama prefecture will be culled after the determination of the highly virulent strain of avian influenza in the case, Kyodo News said.

    Several bird flu outbreaks related with the H5N1 strain have occurred in southern Japan recently. Earlier this month, two cases involving the deadly H5N1 strain were reported in Miyazaki prefecture, where thousands of birds died in two chicken farms, and the rest tens of thousands were culled later.

    The farm ministry reported on Tuesday another bird flu case near the two farms in Miyazaki prefecture, which is suspected to have been caused by the same virus strain.

    Bird flu infections hit dozens of farms in central Japan's Ibaraki prefecture in 2005 and 2006, resulting in the killing of at least 5.8 million poultry.

    The H5N1 strain is a subtype of the influenza A virus that can cause illness in humans and many other animal species. Since the first case of the virus' human infection confirmed in Hong Kong in1997, the strain has infected 265 people in 10 countries and led to death of 159 as of January 13, statistics from the World Health Organization showed.

    It is feared that the bird-to-bird disease of avian flu currently spread around the globe could mutate into a virus transmissible between humans and led to a pandemic.