Taiwan agricultural authorities confirmed Friday chickens in a farm of the island's central Yunlin county were infected with H5N2, a strain of avian flu that poses little risk to humans.

Animal health quarantine official said chances were small for northbound migrant birds to pass the virus to the farm and believed the virus was carried by humans or machinery to Yunlin.

So far, no other chicken farm in the county has reported a similar infection, according to Lu Cheng-chang, an official with Taiwan agricultural authorities.

More than 3,000 chickens have died in the farm over the last three days, prompting authorities to launch an investigation into the cause. The latest has been the sixth H5N2 outbreak in Taiwan this year. Previously, chicken farms in Changhua, Tainan and Nantou were affected by the virus.