Claims that ambulance provision in the far north is to be cut has been denied by the service.
The GMB union claimed the number of ambulances based in Caithness was to be reduced from three to two.
The service currently has ambulances based in Wick, Thurso and Bettyhill.
The union said that a paramedic response unit would replace the lost ambulance.
But the claims have been refuted by the Scottish Ambulance Service, which said they have recently increased staffing in Bettyhill as well as in Golspie and Kinlochbervie in Sutherland.
It said this will help increase cover on shift and reduce the number of staff having to be on call.
The GMB has raised fears that the current arrangement is “totally unsustainable”.
It says that changes at Caithness General Hospital will mean more ambulances being used to make lengthy transfers to Raigmore Hospital in Inverness, further stretching resources.
In a statement issued by the union, GMB Scotland organiser Karen Leonard said: “Let’s be clear that this will only impact public safety, heap further pressure on a workforce being pushed beyond its limits and cannot be conducive in any way, shape or form to help save lives.
“Our ambulance service has been stripped to the absolute bare bones.
“The communities of Caithness deserve so much better and our members need so much more investment and support than they get for the crucial service they provide.
“Quite simply the Scottish Ambulance Service needs to think again.”
However, the ambulance service hit back – saying “there are no plans to reduce ambulance cover in Caithness”.
A spokesman added: “We have recently increased staffing in Bettyhill, Golspie and Kinlochbervie which is enabling us to increase on shift cover and reduce on call working. This will allow us to further improve patient care and staff experience.
“We are working closely with staff and their representatives, including GMB, to develop the detailed shift patterns to support this increase in cover.
“We recently met with NHS Highland, Caithness Health Action Team and the leader of Highland Council to discuss new ways of working to help reduce pressure on the service in the area. We will continue to work with partners and staff to develop sustainable solutions.”