Staffing shortages and COVID-19 precautions are being blamed for an increase in ambulance wait times.
Data released by St John from 2021 also showed an increase in callouts nationwide from 553,286 to 606,503.
St John Deputy Chief Executive Dan Ohs told AM wait times have risen on average by four minutes.
"We are suffering from the same challenges as the whole health sector at the moment, in terms of staffing shortages. We are in the biggest health crisis of our lifetime so the demand for health personnel is very, very high and the number of personnel is one of the things that contribute to wait times," Ohs said on Thursday.
He said the staffing issues are being exacerbated by an increase in callouts and PPE COVID requirements.
"We are also seeing that incidents are taking us longer. So drive times are longer, the process that our people have to do to put PPE on is longer and turn around at ED, with the additional processes associated with COVID, is longer. All of those things are compounding, meaning it is taking us longer to get to some patients."
But Ohs said in the vast majority of cases there are enough ambulances on the road, despite the staffing issues.
"I just want to reassure the public that 97 percent of the time, despite the staffing shortages, we have the right amount of ambulances on the road.
He said wait times for 19 patients are being investigated because they were too long.
"They [19 patients] represent 0.05 percent of the 33,000 incidents we attended in January but even that we want to learn from and do better and even that's too many."
He said the patients were flagged by staff who were concerned there could be a negative clinical outcome from the wait.
Ohs said extra Government funding to scale up for COVID-19 is also helping meaning there are nine more ambulances on the roads across the country than a month ago.
It comes after the Whangarei Emergency Department reached capacity on Thursday.
Northland District Health Board urged locals to only visit if they are "seriously injured or have a serious health concern".
"When you arrive at the Emergency Department you will be triaged by a nurse - if your condition is not urgent you may be asked to wait or advised of other options," The DHB said in a statement.
"There will be a board outlining how long this wait might be depending on the other emergencies that the doctors are dealing with. Patients are seen by order of priority not arrival times.
"ED doctors will treat your condition at the time. You may need to make a GP appointment for any follow up and referrals.
"If you need to get to the hospital urgently you should call 111 and answer the questions as clearly as you can."
