About 20,000 chickens are to be culled after a suspected case of bird flu was found at a farm in County Tyrone.

Disease control measures have been put in place around the site near Omagh and all birds on the farm will be culled.

Samples, which were taken on Friday, are being tested at the National Reference Laboratory to confirm the strain.

Agriculture, Environment and Rural Affairs Minister Andrew Muir said it was a “stark reminder that we cannot afford to be complacent”.

Chief veterinary officer Brian Dooher urged flock owners to adhere to strict biosecurity protocols.

“The disease control measures are crucial to limit any potential spread of disease and I appeal to all bird owners – backyard and commercial – to take all necessary steps to protect your flock,” he said.

“This includes ensuring continuous excellent levels of biosecurity and reporting any suspect cases of avian flu to Daera (Department of Agriculture, Environment and Rural Affairs) immediately.”

Daera veterinary officer Ignatius McKeown said “increasing mortality” at the site led to suspicions about an avian influenza outbreak.

“The house contained 7,000 birds and the mortality increased from three one day to 20 the next day, and then after we had taken samples, the deaths had increased to over 300,” he told BBC News NI.

Mr McKeown said despite the infection being detected in only one house out of three, all birds on the site – estimated to be about 20,000 – will be culled.

“We’re now starting to enter the high-risk period for avian influenza and that is signalled by the movement of migratory birds,” he said.

He urged poultry farmers to review their bio-security measures to prevent further outbreaks.

“Because of the importance of poultry in Northern Ireland, we are always very concerned about outbreaks,” Mr McKeown added.

“This will have a devastating effect on the owner and on the poultry industry.”

It is the first case in a commercial premises in Northern Ireland since February.

Bird flu has continued to circulate in the wild bird population.

Avian Influenza Protection Zone restrictions for the whole of Northern Ireland were introduced in January 2025 after the Highly Pathogenic Avian Influenza H5N1 was detected in wild birds in County Tyrone.

The restrictions were lifted in June.

There were four outbreaks of bird flu in Northern Ireland in February – three in commercial poultry farms in Newmills, Pomeroy and Cookstown, and one in a captive bird collection in Magherafelt.

It was the first time the disease had been confirmed in a commercial setting since December 2021.

The commercial poultry sector is worth around £500m a year to the Northern Ireland economy.