An urgent review into ambulance cover in Orkney is being demanded by MSP Liam McArthur.
It comes after the Health Minister admitted there were 168 occasions last year when emergency calls in the isles were left waiting due to the ambulance responding to another call.
There was one occasion when Orkney was left without any land ambulance cover on the mainland and linked south isles for two hours.
Joe Fitzpatrick, the Minister for Public Health, was responding by letter to questions asked by the Orkney MSP, who raised the concerns last month.
Mr McArthur said: “These figures reveal the extent to which land ambulance capacity in Orkney is failing to meet the needs of patients. People in Orkney will be shocked to hear how often those making emergency calls are being forced to wait due to a lack of land ambulance cover. In many instances, these will be cases where the response time can be critical.
“This is absolutely no criticism of Orkney’s ambulance crews, who do outstanding work in operating a service that is clearly over-stretched. Indeed, the admission from the Minister about the scale of the problem shows that local crews are being let down by a lack of resources and support. This can only be making an already difficult job even more challenging.
“I am due to meet senior representatives of the ambulance service early next month. I will make clear the need for an urgent review into the resources available locally and calling for additional capacity to meet the needs of the Orkney community. This is the very least that the public and our ambulance staff deserve.”
The ambulance service said it is recruiting more staff for Orkney. A spokeswoman said: “The service is committed to providing safe and effective services in Orkney and we are currently recruiting to fill vacancies and remove on call working. This will help our local staff who do a fantastic job to provide more effective 24-seven provision from Balfour Hospital.
“We are also working closely with NHS Orkney looking at ways to increase ambulance cover during peak periods of demand.”
A spokeswoman for the Scottish Government said: “We are working with the ambulance service to increase capacity and reduce individual workload with the investment of almost £900million over the last four years and committing to training an additional 1,000 paramedics over the course of this Parliament.”
