RED squirrels are under threat in Gwynedd after a deadly disease spread across to the county from Anglesey.

A group of around nine squirrels were found on the island and, following tests, they were found to have the highly infectious adenovirus.

The virus, which could have a devastating effect on the squirrel population number, was also found in a dead squirrel near Bangor.

Dr Craig Shuttleworth, of Bangor University, who said sightings of the red squirrel have been spotted near Penygroes and Beddgelert, is concerned for the future of the animals.

He said: “We are in the dark a bit with this virus; it is hard enough to monitor the squirrels as it is but we don’t have enough resources to do as much as we need.

“The discovery of this virus is worrying; we have never had a case before when a virus has spread from the island to the mainland.

“What we know at the moment is that some animals carry the virus but don’t seem to show any symptoms and it hasn’t affected them but they spread it to other animals which then die from it.

“We have so far sent away nine bodies for a post-mortem and four of them have come back with positive results. The bodies of the others were too badly decomposed.

“We will be continuing our investigations into this disease but we are hopeful it won’t spread particularly widely.”

The red squirrel population on Anglesey has increased from about 40 squirrels in 1988 to more than 700 and a wild colony has been established in the Ogwen Valley to try and boost its numbers.