The Nurses Organisation says staff are so overworked their hospitals have become unsafe workplaces.
COVID and underlying staff shortages have left some emergency departments (ED) on half-staffing.
Newshub understands it's far worse in the provinces, because nurses are being poached for shifts in the bigger cities by health managers offering cash incentives.
Nurses Organisation president Kerri Nuku says staff at provincial hospitals like Whangarei are spread too thinly and being asked to do overtime to keep the ED operational.
"This is now asking nurses to work over and above their expected hours of work," she told Newshub.
Nuku said it's the same in many provincial centres. She said Wairarapa ED has run on half-staff while nurses are receiving incentives not available in Wairarapa to cross the Rimutakas and do shifts in Wellington.
"And so where you do have hospitals that are close together and where you have staff who are on the casual pool, they are looking to shift or to move to where they'll get additional pay where they'll do these callback or extra hours," she said.
This shouldn't be happening now the health service has been centralised but Te Whatu Ora - Health New Zealand said how day rates and overtime are applied still differs between regions and moves will be made this week to standardise the incentives so that the provinces can compete to keep staff.
Meanwhile, Nuku said she's heard of nurses being so under-resourced and overworked that they're feeling unsafe in their workplace.
"The health and safety aspect is critical. Not just in terms of the ability for us to provide the quality of care but actually the wellbeing of staff to continue to keep this up."
Health Minister Andrew Little wouldn't speak on camera, arguing it's an operational matter. But National's health spokesperson Shane Reti said there's one quick solution: bring in overseas nurses and give them the right to work here.
"There are a number of levers you can pull, the first is immigration," he said.
Meanwhile the Nurses Organisation says members are telling them every day they hold their breath wondering whether they'll get through their shift.