The HSE's National Ambulance Service (NAS) has said that failures to meet response targets means that some patients can wait for more than two hours for an emergency service response.
A briefing for today's Joint Committee on Health, shows that the worst performing regions last year were the HSE West and North West and the HSE Mid West.
The national target is to respond in 75% of cases of life-threatening cardiac or respiratory arrest (Purple calls) and 45% of cases of life-threatening illness or injury (Red calls) in just under 19 minutes.
In the HSE West and North West region, 64% of Purple calls and 45% of Red calls were made within target.
In the HSE Mid West region, 69% of Purple calls and 46% of Red calls were made within target.
The HSE said that the aim is to have the longest average waiting time brought down from two hours to one hour and is developing a three to five year strategy.
The NAS responded to 430,000 emergency calls last year, up by 10% on last year.
The HSE has also set out ambulance turnaround times after arrival at an emergency department, which on average is 45 minutes.
The aim is to have turnaround within 20 minutes of arrival in 80% of cases and the HSE said it is the responsibility of the relevant acute hospital.
The figure for June this year was that the turnaround target was met in 57% of cases.
Fianna Fáil TD Martin Daly told the committee that he was aware of cases where it took four to five hours for ambulance turnaround.
Sinn Féin Spokesperson on Health David Cullinane said he was concerns that patients can wait over two hours for an emergency response.
