Hundreds of birds are to be culled at a farm in Kent where an outbreak of avian influenza of the H5N2 strain has been detected.
A 1km restricted zone has been placed around the premises near Deal "to prevent the disease spreading".
Public Health England (PHE) said the risk to the UK population was "very low" but it was "looking for evidence of spread to control and eliminate it".
All 480 birds at the site are to be "humanely culled".
The UK's chief veterinary officer, Christine Middlemiss, said: "Immediate steps have been taken to limit the risk of the disease spreading and all remaining poultry and captive birds at the farm will be culled."
There will be no impact on food supply as the farm does not supply poultry, meat or eggs commercially, she added.
Bird keepers have been told to remain alert for signs of disease and to report suspected cases immediately.
"We are urgently looking for any evidence of disease spread associated with this farm to control and eliminate it," Ms Middlemiss said.
Dr Gavin Dabrera, consultant in acute respiratory infections at PHE, said bird flu was an "uncommon infection" in humans.
But he advised people not to touch sick or dead birds and to wash hands thoroughly with soap after contact with any animal.
The Food Standards Agency said properly cooked poultry and poultry products, including eggs, were safe to eat.