The culling of 23,000 chickens at a farm in Suffolk is underway, after avian influenza was confirmed by Defra earlier this week.
Banham Poultry, which is one of the biggest employer in mid-Norfolk, confirmed one of its sites close to the county border in Suffolk was affected.
The outbreak is the seventh case of bird flu in a commercial flock since December, and the first to be found in Suffolk.
Banham Poultry said the birds were being culled and tests were still underway.
“We have had a single case of Avian Influenza (Bird Flu) confirmed on a Suffolk Farm on the evening of Sunday 12 February 2017. The affected farm does not produce meat and is instead a breeding rearer farm.
“The infection was confirmed after we notified the Department for Environment, Food and Rural Affairs following increasing mortality in one of our flocks. They will now be humanely culled by the authorities in accordance with EU legislation. The specific strain of influenza has yet to be identified and further tests will need to be carried out by the authorities before this can be confirmed.
“Birds at our other farms appear healthy and there is no evidence of any spread of infection. All of our staff are trained in biosecurity management and we are ensuring that the controls that are in place are rigourously followed. We will continue to cooperate with the authorities to ensure that the situation remains under control.”