A reported case of bird flu at a commercial poultry farm in County Tyrone is under investigation.
"Significant" mortality and clinical signs consistent with the disease were observed at the site and movement restrictions have been imposed.
Samples have been sent to the national reference laboratory in England for analysis, with results expected on Monday.
The flock will be culled if avian influenza is confirmed.
The Agriculture and Environment Minister Andrew Muir said the situation was being treated with "the utmost seriousness".
The Chief Veterinary Officer Brian Dooher urged all flock keepers of any kind to be vigilant and observe strict biosecurity protocols.
It is the first case this season.
Low public health risk
Bird flu presents little risk to human health but can be catastrophic for poultry flocks.
The commercial poultry sector in Northern Ireland is an important economic player, so the disease is treated very seriously.
The impact this would have on the flock keeper was recognised by the minister.
"While the disease has not yet been confirmed, we are treating this situation with the utmost seriousness.
"We have robust contingency plans in place and stand ready to implement the measures required to respond at the affected premises should Highly Pathogenic Avian Influenza be confirmed," Muir said.
A housing order was introduced in England and Scotland last week, due to the heightened risk at this time of year and a series of outbreaks across Great Britain.
Wales has also brought in restrictions although no cases have yet been confirmed there.
Muir said similar measures have not been ruled out for Northern Ireland.
"In light of these findings, we are actively considering the need for further disease control measures across Northern Ireland, informed by the latest veterinary and epidemiological advice and assessment of risk."
Vigilance required
Dooher said officials stood ready to implement disease control arrangements if the disease was confirmed.
If results came back positive, a cull would be carried out on the farm.
And he encouraged all flock keepers of any nature to take precautions.
"I urge all poultry keepers to remain vigilant, maintain good biosecurity and report any concerns about the health of their birds to DAERA without delay."
While bird flu has already been detected in wild birds this season, this is the first outbreak in a commercial setting in Northern Ireland so far.