The Mountaineering Council of Scotland (MCofS) says Highland Council's planning committee is about to agree "to raise no objection" to the Glenmorie Wind Farm in Sutherland when it meets next week, despite receiving more than 300 objections.
It fears the 34 turbines on the Kildermorie and Glencalvie estates to the west of the villages of Ardgay and Bonar Bridge will ruin the landscape.
At 410ft, the structures will be more than twice the size of Edinburgh's Scott monument, and they will be sited on land from nearly 1400ft above sea level to 2200ft.
The MCof S says the turbines would be "intrusively visible" from Munros (mountains above 3000ft) such as Ben Wyvis, Beinn Dearg and those in the Fannichs.
And they say the report going before the committee next week reflects the pressure being put on councils by ministers to hit the country's ambitious renewables targets.
The report states: "Representations that argue against investment in renewable energy can only be given limited weight given the very positive stance set by the Scottish Government."
MCofS's chief officer David Gibson said: "Unless Highland Council objects in the strongest possible terms to this intrusive proposal, it will demonstrate a lack of stewardship and send a strong message to the renewables industry that the Highlands are open house for massive industrial-scale wind farms.
"We are talking here about one of Scotland's finest mountain areas, an area of outstanding natural beauty."
Because of the project's size, it will be ministers who make the final decision, but if Highland Council objects it would trigger a public inquiry. Planning officials have recommended councillors do not object but propose a long list of conditions.
Natasha Lawrence, project manager for developers Wind Energy, said: "This proposed development has been carefully designed to limit any impact on the surrounding communities and environment."
A Scottish Government spokesman said ministers had taken action to protect outstanding landscapes. "For instance there are no wind farms in our national parks and we require planning authorities to identify areas designated for their national landscape value for significant protection."