The first case of a red squirrel dying in Scotland as a result of the squirrel pox virus has been confirmed.
The squirrel was found displaying symptoms of the virus
The animal, which was displaying classic symptoms of the virus, was found near Lockerbie, Dumfries and Galloway, on Tuesday.
The squirrel was euthanised following an examination at the South of Scotland Wildlife Hospital, Dumfries. Edinburgh vets then confirmed squirrel pox.
The virus is carried by non-native grey squirrels.
Conservationists have been working hard to try and stop the virus coming over the border into Scotland, and until now had been successful.
Intensive control measures have been in place since its presence in Scotland was first detected in invasive populations of grey squirrels in May 2005.
Although the virus is fatal to red squirrels, greys remain unaffected by the disease.
Scottish Natural Heritage currently has two grey squirrel control officers working in the south of Scotland.
Professor Colin Galbraith, director of policy and advice at Scottish Natural Heritage, said: "SNH has been working with the Southern Upland Partnership to monitor the squirrel pox situation in grey squirrels in the south of Scotland for the past six months.
"We were aware that the virus been found in a red squirrel less than a mile south of the border and had feared that, at some point, the disease would transfer to the red squirrels in Scotland.
The red squirrels contract the virus from non-native grey squirrels
"Targeted grey squirrel control in the area has undoubtedly delayed the progression of the disease to Scottish red squirrels and we will continue our intensive grey squirrel control in the affected areas to allow further time to investigate the development of a vaccine."
He said the squirrel control officers would continue to monitor and test squirrels to minimise the spread of the disease.
Local red squirrel conservation officer Ann-Marie MacMaster urged the public to report red or grey squirrels which appeared to be ill.
"Once red squirrels develop lesions, they are extremely infectious," she said.
"We would also ask people in the Lockerbie area especially not to encourage the two species of squirrel together through the use of feeders as this may facilitate the spread of the disease."
Gordon Patterson, biodiversity policy adviser for the Forestry Commission Scotland, said: "We are very concerned about the spread of the virus into red squirrels in Scotland.
"Our staff are already involved in the monitoring work and we will now look out with extra vigilance for any signs of diseased red squirrels in the area and report them to the project team."
Tests on the squirrel's body were carried out at the Moredun Research Institute, Edinburgh.
The red squirrel is one of the most threatened species of mammal in the UK with 75% (121,000 animals) of the population estimated to be found in Scotland.
In February 2007, the Scottish Executive awarded a two-year contract to investigate the development of a vaccine against squirrel pox virus.