The holding company represents the interests of the Buccleuch family headed by the current Duke of Buccleuch, Richard Scott, the 10th Duke, who is the largest private landowner in Scotland with some 280,000 acres (1,100 km2).

The area to be sold off stretches from Auchenrivock in the south to Hartsgarth in the north - much of it currently part of the group’s farming operations.

The company said it would consult local communities about the plans with a questionnaire to be made available online or in local community hubs.

Buccleuch Estates said the land included a “small number” of farm tenancies which would continue under any new ownership along with blocks of forestry.

The area involved also contains Langholm Moor which has been the site of two major scientific projects into moorland management.

Benny Higgins, executive chairman of Buccleuch Group, said: “The completion of the Langholm Moor project gave us an opportunity to look at what the moor’s future should be within the wider Buccleuch portfolio of landholdings.

“That review led us to the conclusion that marketing the moor area for sale was our preferred option.

“The decision is very much in line with our business’s stated aim of reducing the Buccleuch footprint while enabling us to invest in priority projects.”

The Borders Estate - which contains the land involved - was formed last year by the merger of the old Bowhill and Eskdale & Liddesdale estates

Andrew Thin, chair of the Scottish Land Commission welcomed the announcement by Buccleuch.

He said: “Buccleuch Estates has committed to reduce its overall footprint and it is good to see the Estate undertaking community engagement to help inform the next phase of proposed land sales. The Estate will be using the Land Commission’s first Land Rights and Responsibilities Protocol ‘Community Engagement in Decisions Relating to Land’ which sets out practical advice on how landowners, land managers and communities can work together to make better – and fairer – decisions about land use.

“Scotland’s Land Rights and Responsibilities Statement sets out a clear ambition about the relationship between land and people in Scotland promoting greater diversity in ownership of land including more community ownership, high standards and transparency of land ownership and use and better community engagement in decisions about land.  We welcome the announcement by Buccleuch as a step in achieving this ambition and we encourage other large scale land owners to consider a similar approach.”

Buccleuch has instructed Savills to handle the proposed sale.