The Ministry of Defence has objected to contentious plans for a major windfarm at a rural Buchan landmark.
Proposals to put up 12 turbines on the slopes of Mormond Hill, between Strichen and Fraserburgh, have already divided opinion.
Developer Muirden Energy claims the 330ft masts would generate enough power for thousands of homes and could pump around £50,000 into local projects each year.
But campaigners who launched their own action group to fight the plan say the masts will destroy one of the north-east’s most spectacular sites.
Now the Defence Infrastructure Organisation, the recently launched property arm of the MoD, says it cannot support the scheme as it could cause “unacceptable interference” to radar equipment at RAF Buchan, 14 miles away.
In its objection to local authority planners, assistant safeguarding officer Claire Duddy states: “Trials carried out in 2005 concluded that wind turbines can have detrimental effects on the operation of radar which included the desensitisation of radar in the vicinity of turbines.
“The probability of the radar detecting aircraft flying over or in the vicinity of turbines would be reduced and the RAF would be unable to provide a full air surveillance service in the area of the proposed windfarm.”
The MoD said that, if a compromise can be reached with the developer, the turbines should be fitted with lights to make them more visible.
The Mormond Hill summit was home to a Nato radar station during the Cold War and there is still evidence of telecommunications machinery.
Muirden’s application for planning consent is being considered by Aberdeenshire Council officials and is likely to be brought before local councillors in the new year.
Planners have received 10 letters about the scheme, including six opposing it.
The Strichen Community Park Company has also objected to the plan.
The Turbine-Free Mormond Hill campaign group held a series of public meetings last month to raise their concerns about the plan.
Organisers said the turn-out at the four sessions was lower than expected.