Patients are facing eight hour wait times for ambulances to arrive because of knock-on effects from the hospital system.
SIPTU Ambulance Sector President Greg Lyons said the delays are because patients are not being discharged from ambulances into Emergency Departments.
It comes after an elderly patient in the south-west waited over four hours with a broken hip for an ambulance.
Mr Lyons told Newstalk Breakfast such delays are more common than they'd like to see.
"It's more prevalent at the moment due to increase surges in hospital demands in EDs, so we tend to have more waits in EDs for longer periods of time," he said.
"[This] obviously leave us more vulnerable to getting the calls that are outstanding and our own communities are affected by that.
"So, it's more common than we would like to see".
An ambulance outside Leinster House in Dublin, 29-06-23. Image: Sam Boal/Rollingnews.ieMr Lyons said there are always issues with the service.
"We've an under-resourced ambulance service, we've an underfunded ambulance service," he said.
"We've a low-paid, highly skilled workforce, we have ongoing HR IR issues, we have lack of investment in fleet.
"Presently I suppose the key thing is the hospital surges is what's holding us up with four eight-hour delays on a regular basis for a multitude of ambulances.
"There's 90 extra ambulances needed on a daily basis to provide the demand."
'Systemic problem'
Mr Lyons said waiting times at Emergency Departments is just one of the issues they're facing.
"Unfortunately it's a systemic problem, so when EDs are delayed and shuffling people from EDs up to hospital beds, hospital wards we feel the knock-on effect," he said
"Our staff, ambulance professionals, aren't released - so patients remain on our beds.
"We can't follow through the system, clear the call and go to the next call, that's always outstanding," he added.
Mr Lyons said while there is no easy solution, investment is key.
