Senior doctors are being forced to pick up junior doctors' shifts on top of their own work, as hospitals grapple with hundreds of vacancies.
The Association of Salaried Medical Specialists, which represents the country's 5500 senior hospital doctors and dentists, said this meant they were unable to do their own work, and many were burning out from the unsustainably long hours.
Executive director Sarah Dalton said their contract had always allowed for senior doctors to provide cover for their junior colleagues from time to time as required.
"But what was meant to be an exception has become 'business as usual'."
Te Whatu Ora Capital and Coast and Hutt Valley had been looking to implement a formal agreement for senior doctors to do junior doctor shifts, she said.
"We are absolutely opposed to that and we're really concerned about any attempt to normalise senior doctors being routinely asked to agree to cover the work of missing junior doctors."
Picking up this other work left consultants and specialists no time for teaching, supervision or planning and development of services.
"SMOs [senior medical officers] are routinely pressured to pick up extra work and it's not unusual for it to be suggested that if they don't, patients will suffer.
"Now that's a really terrible pressure to put on senior doctors."
Senior doctors and dentists are about to get their first pay rise in more than two years, with their union expected to ratify a hard-won collective agreement any day now.
However, on the picket-lines in September during their unprecedented strike action, doctors were clear it was not just about the money.
Speaking to RNZ at the time, Hutt Hospital obstetrician-gynaecologist Ed Hyde said staff shortages meant some hospitals "can't even be safely staffed overnight".
"I was on call yesterday, I'm working this weekend. So that's 24 hours yesterday and 48 hours over the weekend."
Te Whatu Ora estimates the health system is short about 1700 doctors in total, of which approximately 200 are the more junior Resident Medical Officers or RMOs.
However, Resident Doctors' Association head Deborah Powell said that was a "massive undercount".
"We have over 400 vacancies for resident doctors across New Zealand. We have been double shifting and picking up additional shifts. But unfortunately our hours are creeping up as a result of that, and starting to get back to the bad old days of 60, 65 hours a week."
Before Covid-19, 40 percent of RMOs were from overseas, on temporary working holiday visas.
But they were no longer flocking here - and many local graduates were heading straight to Australia.
Powell said that trend had accelerated since the nurses' pay settlement.
"A graduate doctor is now paid less on an hourly rate than a first-year nurse, and that's for the first two years of their career.
"That's not a problem with what the nurses are paid - it's a problem with what the doctors are paid. And that's also fuelling discontent."
In May, Te Whatu Ora announced plans to pay junior doctors, up to $220 an hour to volunteer for weekend and night shifts on top of their usual workload, to nurse the health system through winter.
It expected the temporary "enhanced rates" would cost up to $16 million over five months.
However, a spokesperson said the agency now acknowledges vacancies for junior doctors are likely to continue for some time while various recruitment efforts continue, and it has extended the scheme until March next year.
"In order to cover the resulting roster gaps, RMOs are initially offered additional duties - which will lead to an increase in hours worked.
"When a gap remains on the roster, particularly after hours and on weekends, SMOs from the relevant speciality may be asked to undertake tasks a RMO would otherwise have done. This is standard practice around the country."