Selling Prestwick Airport to the United States military should be ruled out by ministers, the Scottish Greens demanded today.
But transport secretary Michael Matheson refused to respond to the call, saying that commenting on who might be bidding could "infringe" the sale process.
Greens transport spokesman John Finnie challenged him at Holyrood's connectivity committee: "Will the Scottish Government rule out selling Prestwick Airport or any part thereof to the US military?"
It followed the revelation that the debt-laden South Ayrshire airport's main income comes from US military flights.
Mr Matheson responded: "We are in the middle of a process where the management team at Prestwick Airport has advertised the airport for sale.
"What I am not going to do is enter into speculation about who, if anybody, would be purchasing the airport because it could infringe on the integrity of that process.
"I don't want to be evasive but I'm trying to protect the process the management team are undertaking, so I am not going to enter into any speculation about any potential purchase or purchaser of the airport."
Mr Finnie later condemned the response as "scandalous".
He said: “The Scottish Government has an obligation to uphold international human rights law and there is considerable concern it has failed to do so in the past at airports it owns including Prestwick, Wick and Inverness.
“We know Prestwick Airport has facilitated active US military missions and extraordinary rendition flights,
"I am told the Lord Advocate is still investigating the latter, and that the US Military is its largest customer.
“The cabinet secretary’s failure to rule out selling the airport to the US military is absolutely scandalous and leaves open the possibility that such human rights violations could continue unhindered in future.”
Fellow committee member Scottish Liberal Democrats transport spokesman Mike Rumbles said after the meeting: “Being beholden to the US military makes the airport even less viable to prospective buyers and confirms the only commercial [passenger] operator using the airport, Ryanair, is not the airport’s largest single income source.
“Despite £40 million of Scottish Government support since 2013, Prestwick Airport is still failing to become a viable business.
"Along with the airport's potentially controversial dependence on the US military as its largest customer, there will be serious concerns for any company looking to purchase the business.
“The Scottish Government has failed to encourage commercial operators to fly from Prestwick and now it needs come clean about whether the airport is really a feasible business.”
Mr Matheson also revealed to the committee it was the airport, not its Scottish Government owner, which had requested it be formally put up for sale three months ago,
Up to three offers are being assessed following the deadline for full bids last Friday.
The sale is due to be completed early next month.
Mr Matheson said the airport had been advertised for sale because "a number of parties" had expressed interest in Prestwick "as an aviation facility".
He said as a result, it was decided it was "a good time to test the market to see exactly how concrete that interest was".
Mr Matheson said: "That was the reason why we agreed to the request from Glasgow Prestwick's management team to issue a notice for any interested parties to express an interest."
Glasgow Airport has told The Scotsman it did not bid, but Edinburgh Airport has refused to comment.
The minister also refused to tell Scottish Conservatives' transport spokesman Jamie Greene whether a buyer would have to repay nearly £40 million of Scottish Government loans.
The borrowing has been provided since the airport was nationalised six years ago to avert its closure and hundreds of job losses.
He said: "Given the sensitivity of where we are in this process, I'm not going to get drawn into any scope around speculating about any potential for the purchase of the airport, largely because it would suggest we had taken a particular position on the matter during a live process of considering any interests in the airport."