The death of a 57 year-old man at Encounter Bay this morning is the subject of an alarming claim by the Ambulance Employees Association (AEA).

The union says he may have been saved if an ambulance with a defibrillator had been able to arrive sooner.

All crews in the area were attending other call-outs and the union claims that no extra crews had been rostered to work over the busy Easter period.

The man had been scuba diving and collapsed on the beach as he returned to shore.

Emergency services were called to the scene just after 11am but it took almost 25 minutes for an ambulance to arrive.

The union says three police officers tried to resuscitate the man. They also posted copies of messages on their Facebook page showing police requesting a defibrillator from the South Coast Hospital or a football club.

The full text from the AEA Facebook post says, "Today a triple zero call came in just after 11:00am for a patient who was in cardiac arrest in Victor Harbour after scuba diving."

"It took almost 25 minutes for an Ambulance to arrive. There were no Ambulances available; all were out on cases. The Ambulance should have arrived within 8 minutes.

There were no extra crews at Victor Harbour despite the influx of thousands of holiday makers.

"Three police officers on scene trying to resuscitate.

"The AEA is informed that the patient might well have been saved if an ambulance arrived with a defibrillator and lifesaving medical equipment sooner.

"This poor patient was not given the best chance of survival.

"This is an absolute tragedy for the patient, their loved ones, and traumatising for the Police Officers and our Triple Zero Call Takers.

"The AEA and all its members extend their deepest sympathies to the patient’s family and their loved ones.

"Sadly, this has happened many times before, the Marshall Government's refusal to properly fund the ambulance service is a factor in this, not ambos working conditions.

It is the very reason we marched on Parliament House on Thursday, to try to stop this happening again and again."

Police are preparing a report for the coroner.