Calls have been made for a government review of controversial plans to centralise air traffic control after it emerged that £6 million had been spent on the scheme.
Highlands and Islands Airports Ltd (HIAL) has proposed controlling air traffic at six regional airports from Inverness by 2023.
The agency has purchased a site in the city for a remote tower, which will house a combined surveillance centre.
The shift would leave towers unmanned at island airports including Sumburgh in Shetland, Kirkwall in Orkney, and at Stornoway and Benbecula in the Western Isles.
New figures obtained from HIAL through a freedom of Information request by Shetland News revealed more than £6m has so far been spent on the controversial project.
A sum of £2.6m of that was spent on the purchase of New Century House in the Highland Capital, as well as more than £341,000 on consultancy fees.
Shetland MSP, Beatrice Wishart, a prominent campaigner against the plans, said it was “disheartening” to see millions of pounds being spent on a project which could potentially reduce employment on the island.
She said: “To see that over £6m has been spent on a project that could potentially take highly skilled jobs away from Shetland is incredibly disheartening.
“Serious and legitimate concerns about the project to centralise air traffic control have been raised repeatedly but HIAL is intent on pressing ahead.
“Further costs for this project have the potential to spiral further.
“The Scottish Government should re-assess this project to find the best modernisation solution for the Highlands and Islands and should listen to the local communities who have been so forthright in their opposition to it.”
The revelation comes as executives prepare to give evidence to Holyrood’s public petitions committee about the extensive plans.
Molly Nolan, Scottish Liberal Democrat candidate for Caithness, Sutherland and Easter Ross has also spoken out against the plans which would mean the service at Wick Airport is downgraded.
Mrs Nolan is calling for the government to step up and demand a review into HIAL and its “obsession with centralisation”.
She said: “Highlanders, myself included, are sick of seeing everything centralised in Inverness.
“Instead of consulting local communities to find a way to retain skilled jobs, they march on with a top down and extremely expensive centralisation plan which everybody knows will be a disaster for our regional airports.
“If the SNP really care about the success of Wick Airport, they need to exercise their power over HIAL and force them to review this obsession with centralisation.”
A spokesman from HIAL said: “We have undertaken this project to ensure the long-term sustainability of all our airports, while at the same time securing air services to the Highlands and Islands for generations to come.
“The programme is on budget and on schedule.
“HIAL has already invested millions of pounds to improve Wick John O’Groats airport and is committed to its future success.
“We will continue to work closely with the Highland Council, aviation partners and the local community to help introduce air services that best meet local needs.”