Officials in Japan have confirmed that a recent outbreak of bird flu at a poultry farm was the deadly H5N1 strain of the virus.
Officials said birds on neighbouring farms would also be culled
The outbreak, at a farm in Hyuga, is the second to strike Japan's main chicken-producing region of Miyazaki.
Samples taken from 3,000 dead chickens from the farm revealed that all had been infected with the H5N1 virus.
Officials said they had begun slaughtering the farm's remaining 49,000 birds on Friday.
A further 50,000 chickens from a farm neighbouring the one that suffered the outbreak will also be killed as a precautionary measure, an official said.
There have been a number of H5N1 outbreaks in Japan since early 2004, but there have been no human deaths from the virus.
The earlier H5N1 outbreak occured in mid-January at a farm in the same region.
Health officials across Asia are on alert as a growing number of countries have reported cases in both birds and humans in recent weeks.
Since the H5N1 virus emerged in South East Asia in late 2003, it has claimed more than 150 lives around the world.
There are fears the virus could mutate to a form which could be easily passed from human to human, triggering a pandemic and potentially putting millions of lives at risk.