Japanese authorities have confirmed that a bird flu outbreak in the country's south was caused by the deadly H5N1 virus.

Authorities said Saturday officials are culling tens of thousands of birds on the affected poultry farm in Miyazaki prefecture.

The culling began Friday, after preliminary tests showed the chickens were infected with an H5 strain of the bird flu virus.

Earlier this month in the same area, Japan confirmed its first outbreak of H5N1 in three years.

No human infections have been reported.

Bird flu has killed more than 150 people worldwide since its emergence in 2003.