The process of putting Caledonian MacBrayne ferry services out to tender has cost the Scottish taxpayer more than £15m, it has been revealed.
Millions of pounds have been spent on tendering the routes
The figure, more than half the annual subsidy for CalMac, was obtained by the SNP from the Scottish Executive.
CalMac has been the only bidder for the package of more than 20 Clyde and Hebrides routes.
The executive insisted it had no choice but to go ahead with the tendering process under EU competition law.
The SNP's transport spokesman Fergus Ewing said the executive had wasted millions of pounds because the tendering process was not legally necessary.
"Other countries in Europe did not go ahead with tendering and were not penalised," he said.
"The executive were supine in the face of pressure from the European Commission, the only pressure being that someone may sue the executive."
The costs were obtained by the SNP's Jim Mather, who said the expense was regrettable and entirely avoidable.
Mr Mather said ministers could have mounted a much stronger defence against the EU's demand that the routes were put out to tender.
Scottish Conservative transport spokesman David Davidson said the Labour/Lib Dem executive's handling of the tender had been a "farce from the start".
He said: "Successive Lib Dem transport ministers have taken a frivolous attitude to the use of taxpayers' money, and Tavish Scott should now consider his position very carefully."
A Scottish Executive spokesman said its priority was always to protect lifeline ferry services.
He said: "We were presented with no alternative but to tender in order to ensure that the subsidy was in line with European law.
"Tax liability was an inevitable part of the tendering process.
"Restructuring was an essential part of the tendering process and was required to keep the routes securely in public ownership."
A spokeswoman for the Scottish Liberal Democrats said: "Tavish Scott has made his views on the tendering process very clear.
"This money would have been better spent improving public services."