The average response time in NSW for code one emergencies in 2018/19 was 24 minutes which was Australia's second slowest behind Tasmania, according to a Productivity Commission report released on Friday.

The Australian government report stated this was the longest wait time recorded in NSW in a decade.

Tasmania recorded an average wait time of 29.2 minutes.

Ambulances in Sydney also had the slowest capital-city response time for code one emergencies, with patients waiting 21.3 minutes in 2018/19.

Perth in WA recorded the fastest capital-city wait time at 14.7 minutes.

The NSW Health Services Union argued population growth was placing increased strain on the state's ambulance service.

"Our paramedics are cracking under the strain of more intense workloads and budget cuts," HSU NSW secretary Gerard Hayes said in a statement on Friday.

"Our paramedics are dealing with ever more complex problems such as slower traffic, higher density living and declining air quality."

He called on the Berejiklian government to inject additional funds into the state's ambulance service and hire more paramedics.

A NSW Health spokeswoman said the state was "leading the way or on par with the rest of the country" in other areas of the report.

"NSW has the highest level of patients seen within emergency department triage benchmark performance times of all jurisdictions, with 78 per cent of all patients seen on time in 2018/19, compared to 71 per cent nationally," the spokeswoman said in a statement.

"NSW also had the lowest percentage of all jurisdictions for patients with an extended wait (three per cent) for patients admitted from the elective surgery waiting lists in 2018/19, well below the national result of eight per cent."

Australian Associated Press