There has been a 30% rise in 999 calls since last year
The Isle of Wight Heathcare NHS Trust is failing to meet government-set response targets of answering 75% of life-threatening calls within eight minutes.
The trust says its efforts are being hampered by a 30% rise in call-outs since NHS Direct was made available to islanders.
NHS Direct denies it is advising people to call out ambulances without good reason.
Malcolm Hunter, general manager of emergency and diagnostic support services for the trust made his claim at a meeting called by the Isle of Wight Community Health Council (CHC).
It was held in response to reports that the trust was planning changes to its ambulance cover in an attempt to reach the targets.
But Dr Mike Sadler, director of NHS Direct, said he did not believe they were advising people to call out the ambulance service unnecessarily.
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The service is currently meeting 60% of all life-threatening calls within eight minutes, compared with a national average of 73%.
Case details
Callers to NHS Direct can be advised to care for their complaint at home, see an out-of-hours GP, go to accident and emgency, call an ambulance, or make an appointment to see their GP during surgery hours.
Dr Sadler said: "What we have said to the ambulance service is please send us any details of a case where we have advised to call the ambulance service that they don't think was appropriate and we will look into it.
"All our calls are taped, we can follow the process very, very clearly and if we find problems we will ensure they are acted upon.
"Up to now [Isle of White Healthcare NHS Trust] have not provided such details."
Different view
Paul Barber, chief officer of the Isle of Wight CHC, told BBC News Online, the trust and NHS Direct, had to agree on the true situation.
"If there is a problem then something needs to be done about it.
"At the moment there seems to be some debate about the figures and NHS Direct have taken a different view to the figures quoted by the healthcare trust."