Fresh fears have been raised that UK transport chiefs could axe the emergency tug stationed off the islands.
Towing vessels were recommended to be stationed off Scotland’s coast as part of the inquiry into the Braer disaster of 1993, but have been at the centre of controversy in recent years.
UK ministers provoked anger in 2010 when they announced plans to pull funding for the two tugs based at Stornoway and Lerwick, before being forced to partially back down and restore one of them.
However, the contract for the remaining vessel – which is now based at Orkney – is due to expire in April.
Former Scottish Secretary Alistair Carmichael, the MP for Orkney and Shetland, yesterday wrote to the Transport Secretary Patrick McLoughlin asking him to outline his plans for the future of the tug.
The Liberal Democrat demanded answers after the government made no reference to the contract in its spending review on Wednesday.
Mr Carmichael said: “The retention of the emergency towing vessel is absolutely vital for maritime safety in the northern isles, yet, once again, we find its future is unclear.
“Just this week, the tug was deployed to assist a vessel which had got into difficulties off the west coast of Orkney.
“This is another reminder of the value of the service, and you only have to recall the disaster of the Braer grounding to appreciate its importance to the northern isles.
“I have made the case for extension of the contract a number of times to the transport secretary, and I had hoped this spending review would have provided us with some certainty.
“Sadly this was not the case and time is now running out for renewal. If the contract is not to be renewed then that needs to be known well in advance.”