More people might die during emergencies unless extra funding is pumped into ambulance services in NSW, the Health Services Union (HSU) warns.
The comments came after Fairfax Media on Tuesday published a "confidential" report from the Ambulance Service of NSW that outlined the consequences of failing to build new stations amid Sydney's growing and ageing population.
The document, which reportedly called for more funding in the 2011/12 state budget, says $130 million is needed for 20 new stations for Sydney by 2020.
The HSU's Gerard Hayes says the report confirms the "urgent" need for more investment in paramedic services.
"Paramedics are highly qualified and highly skilled to deliver life-saving treatments on the roadside," he told AAP.
"If there are not enough numbers of them or there's not enough stations to accommodate them in growing areas, more people can die."
He said paramedics were attending to about 50,000 extra jobs every year and were "stretched beyond belief".
"Unless we want response times to blow out further, we need urgent investment," Mr Hayes said.