CalMac challenges Northern Isles ferry service decision
Caledonian MacBrayne is challenging the Scottish government's decision not to give it a contract to run Northern Isles ferries.
Serco won a six-year contract in 2012 and it was named the preferred bidder to continue the service last month.
However CalMac, which is owned by the Scottish government, says its tender was cheaper than Serco's.
Transport Scotland said the row will not affect a promise to discount cabins for islanders and freeze fares.
The contract, due to run for at least the next six years and worth an estimated £450m, is to run publically subsidised lifeline routes between Aberdeen and Lerwick and Kirkwall, and from Scrabster to Stromness.
The government say the decision on who won the bidding process was 65% based on price, and 35% on the quality of the bids.
The final award of the contract is currently on standstill.
A spokesman for CalMac's parent company David MacBrayne said: "Having won the tender for the Northern Isles ferry services on price, we are in dialogue with Transport Scotland".
In a statement they added that the company was now "analysing the detailed information we requested from them about their scoring process.
"As we are still in what is now an extended standstill period, we cannot comment further."
In a statement, Transport Scotland said the bidding process was designed to "attract the most economically advantageous tender based on a combination of price and quality."
A spokesperson said: "(Since) this is a live procurement, there is a limit on what can be said at this time, however more detailed information will be provided in due course and when it is more appropriate to do so."
Orkney's MSP Liam MacArthur told BBC Radio Orkney that CalMac "are within their rights to challenge the decision". But he called on ministers to deal with the complaint quickly.
"The future of these lifeline ferry services has already been subject to an 18 month delay, with all the inevitable uncertainty that has created", he said.
"Any further delay is therefore disappointing and should be kept to a minimum.
"Businesses and those in the Northern Isles who depend on these lifeline services deserve nothing less and cannot continue to be left in limbo".
Serco said it didn't want to comment on the issue.
The new contract to run the services is due to come into effect at the end of October 2019.