A second outbreak of a fatal red squirrel disease has been confirmed in Glenarm Forest in County Antrim.
It follows an outbreak of squirrel pox in County Down three months ago.
The disease is carried by the non-native grey squirrel which is immune to its effects. Infected red squirrels die within 15 days of contracting the virus.
The disease has already had a devastating effect on native red squirrel populations across the UK.
Northern Ireland Environment Agency (NIEA) Senior Wildlife Inspector, Dr Declan Looney said it was becoming a real cause for concern.
"The previous outbreak was three months ago and over 80 miles away in County Down," he said.
"We are monitoring the situation but would ask for the public to remain vigilant and immediately report any squirrels showing signs of the disease to the NIEA wildlife team or to a member of the NI Squirrel forum.
"Many of our native species such as the red squirrel are increasingly under pressure and it is very important that we do all we can to protect them".
John Griffin from Dard's Forest Service, added: 'We will urgently begin work with the adjacent landowner Antrim Estates, the Glens Red Squirrel Group and the other partners within the Northern Ireland Squirrel Forum to implement control measures to safeguard the local red squirrel population at Glenarm.
"We acknowledge the dedication and vigilance of the Glens Red Squirrel Group which resulted in the discovery of the two suspect cases.'
The decline of red squirrels in the UK is blamed primarily on the effects of squirrel pox as well as the loss of woodlands and competition from grey squirrels.