Officials in Kagawa Prefecture, western Japan, say dead birds found at a local poultry farm have tested positive for bird flu in a preliminary check.
The officials received a report from the farm in Sanuki City on Wednesday that 55 chickens had been found dead.
Preliminary tests showed that 3 out of 11 samples were positive for the type-A strain of the flu virus.
The firm has since stopped moving its chickens, and officials are conducting further testing.
If infections are confirmed, the officials will cull 51,000 birds at the farm and carry out tests at 8 other farms within a 3-kilometer radius.