CHICAGO: A commercial chicken flock in Kentucky tested positive for a highly lethal form of bird flu, officials said on Monday, widening an outbreak that threatens the US poultry industry.

Infections in the chickens being raised for meat are set to trigger more restrictions on US poultry exports, after buyers like China and Korea limited purchases from Indiana last week due to an outbreak at a commercial turkey farm there.

The broiler chickens in Fulton County, Kentucky, located near the border with Tennessee, were infected with the same H5N1 strain of highly pathogenic avian flu as the turkeys in Indiana, Kentucky officials said.

They are awaiting final lab confirmation of another suspected outbreak among turkeys in Webster County, Kentucky.

Birds from infected flocks will be culled and will not enter the food system, state officials said.

“We are working diligently to prevent this virus from spreading to other poultry premises,” said Katie Flynn, Kentucky’s state veterinarian.

Federal and state authorities are testing commercial and backyard poultry flocks nearby in Kentucky and Tennessee.

The disease was also detected in a backyard flock of birds in Fauquier County, Virginia, that have already been culled, the US Department of Agriculture said. The cases do not present an immediate public health concern, the agency said.

Wild birds are thought to be spreading the virus, after dozens tested positive for the flu along the US East Coast.