Northern Isles MP Alistair Carmichael has raised questions about an apparent delay in the launch of emergency towing vessel (ETV), to help in the search for survivors of the Cemfjord.
The Cypriot-registered cargo boat sank this weekend with a cargo of cement. She had eight crew on board, now feared dead.
The major search and rescue operation ceased last night and the Marine Accident Investigation Branch is looking into the incident.
Mr Carmichael said the Herakles, moored at the Hatston pier in Kirkwall, may have only departed its berth two and a half hours after the alarm was first raised.
The search involved helicopters, lifeboats, five local coastguard teams, the Royal Navy frigate, HMS Somerset and the passenger ferry Hrossey, who was first to raise the alarm on Saturday afternoon.
Mr Carmichael said: “The loss of the cargo ship Cemfjord was a sad way to start the New Year and, like everyone I speak to, my thoughts are firstly with the family and friends of the missing crew.
“We are, as ever, grateful to the crews of the lifeboats, helicopters, the emergency tug, and local coastguards for everything they did in the hours and days following its discovery.
“A number of local people have raised their concerns with me that the ETV left its mooring two and a half hours after the alarm was first raised by the Hrossey.
“I am wanting to know, first of all, if this is true and, if it is, what the reason for the delay was. Obviously the tug is not a lifeboat and is used differently but if it was necessary to use it in this operation then I would like to know why there was this delay.
“It is important for the local community to have confidence in the tug and the way that it is being used. These questions, therefore, cannot be left unanswered.
“I have been in touch with the Maritime and Coastguard Agency already and shall now be raising these fresh concerns with them.”