Pembrokeshire's Conservative Assembly Members are worried that four in ten ambulances in the county are taking longer than eight minutes to respond to emergency 999 calls.
New figures show that 59.5 percent of ambulances called out during July arrived on the scene within the target time of eight minutes.
"Our ambulance crews are doing a great job but many are still not reaching emergency call outs such as suspected heart attacks within eight minutes," said Preseli Pembrokeshire AM Paul Davies.
"I appreciate that we live in a rural county which brings its own set of problems and that we have a great number of visitors during the summer months which also adds pressure.
"However it is alarming to think that of every 10 people who call an ambulance to an emergency, four of them will have to wait longer than eight minutes for a response."
It was a similar story in Carmarthenshire where 61 per cent of ambulances reached their destination within the target time. Carmarthen West and South Pembrokeshire AM Angela Burns added:
"What is of concern is that we didn't experience a swine flu outbreak during in July and it is a relatively quiet time of year for the emergency services. I hope this does not mean that waiting times will get considerably worse during the busier winter months.
"The Assembly Government cannot expect standards to improve when it is asking the ambulance service to make millions of pounds worth of efficiency savings.
"If it were not for the hard work and dedication of ambulance crews the situation would be considerably worse."
