MINISTERS have cut the frequency of a lifeline ferry service connecting Orkney to the mainland days after winning a legal battle over the awarding of a six-year ferry contract to private operator Serco.

The crossing over the Pentland Firth between Scrabster, near Thurso, to Stromness will go from three sailings a day in each direction to two, though the current timetable will be retained during the busy period between mid-June and mid-August and during some bank holiday weeks and Easter.

Transport Minister Keith Brown said the sailings would be "better aligned with known demand" and followed consultation. But the move prompted anger from the leader of Orkney Council and politicians.

Serco was selected as the preferred bidder for the ferry contract in May. However, the decision was put on hold following a challenge by rival bidder Streamline and was only confirmed following a hearing at the Court of Session this week.

Liam McArthur, the Liberal Democrat MSP for Orkney, said: "Keith Brown promised better services. It's difficult to square that with a 20% cut in overall journeys. This is a lifeline service. Sometimes it is less full than at other times but it can be absolutely critical service."

Mr McArthur said the move would result in passengers having to stay overnight if travelling to the central belt as many would not be able to make coach and train connections.

Steven Heddle, convenor of Orkney Islands Council, disputed claims that it had been consulted on the changes. "Far from endorsing a reduction in daily sailings on the Pentland Firth route, we said to ministers that consultation would be required before such a move was put in place," he said.

In an open letter, Mr Brown said: "Council officials suggested that three return sailings per day during the off-peak periods was recognised as over provision and that a reduced number of sailings during the off-peak periods would better meet demand."