BERLIN, Aug. 28 (Xinhua) -- The bird flu found on a southern German farm last week has infected more poultry than previously thought, local authority said Tuesday.

    Tests show that birds in three enclosures, instead of only one, in the farm near the southern German city of Erlangen have been infected with bird flu, director of the local veterinary authority Ottmar Fick said Tuesday.

    However, it was unclear whether all these birds were infected with the deadly H5N1 virus, which experts believe could transfer to humans, he said.

    Earlier reports say some ducks which died suddenly in the farm have been tested positive for the H5N1 virus and experts are still trying to find out where the virus originated.

    Meanwhile, Fick said it was not clear whether infected birds had been offered for sale commercially.

    "We cannot exclude delivery," he said.

    All the 166,000 birds on the farm were killed after bird flu was identified on Friday.

    Several cases of the deadly H5N1 strain in wild birds has been identified in the German states of Bavaria and Sachsen in June.

    According to the World Health Organization, 195 people globally, mostly in Asia, have died from the H5N1 virus.