Nurses working in chronically short-staffed hospitals say staff who go on leave, get sick or quit are not being replaced in many cases.

Health New Zealand insists recruitment has continued while it has been revising its budgets to find millions of dollars in savings - but front-line workers say job ads and even verbal offers have been "ghosted'.

Waikato Hospital emergency nurse Tracy Chrisholm said some patients were waiting 20 hours or more to be seen.

"In the last two to three years I can't remember coming in for a shift where we've had no-one at six hours plus."

There were simply not enough nurses, doctors or allied staff, she said.

"We have multiple people on maternity leave, we've had multiple resignations that haven't been signed off to be advertised and re-employed or covered because we're above our budget."

Chisholm - who is also a delegate with the Nurses Organisation - said Waikato ED should have an extra 40 full-time nurses on top of its budgeted allocation of about 117, according to calculations based on real-time patient numbers and workload.

At the start of the year, hospital managers agreed, and allowed the department to recruit "ahead of budget".

But that came to an abrupt end in July, when Health Minister Shane Reti replaced Te Whatu Ora's national board with a commissioner, Dr Lester Levy, and charged him with finding $1.4b billion dollars in annual savings.

At the time, Health NZ chief executive Margie Apa publicly attributed its $130m a month "over-spend" to being "ahead of budget" on nursing recruitment.

Chisholm said many wards had gaps in the roster every day, but the real shortfall was much worse than the official figures showed.

"We could probably say there are between 20 and 30 ghosted positions," she said.

"They like to say there's a delay in advertising or a delay in the approval process or we're 'over budget' so we need to pause for a moment."

At one point, every new appointment had to be signed off at national level, but then recruitment was devolved to a regional panel with a set allocation for each workforce, and clinical leaders forced to "prioritise".

RNZ has seen documents for Wairarapa Hospital showing that in June, there were requests for 19 full-time staff in nursing, but only six positions allocated.

Wairarapa nurse Amber Cox, another union delegate, said the hospital officially had 1.5 full-time equivalent nursing vacancies on 30 June - but staff calculated the real shortage was about 40.

Whenever anyone left, the department had to get permission to apply to have them replaced.

"[They say] you don't have enough money to fund that nurse because you've already spent your budget - even though it was under-budgeted in the first place.

"So we can't allow you to appoint to that position, therefore that position doesn't exist.

"You get this impression they're trying to retract or shrink the nursing workforce.

"And they look like they're fully staffed, because they've just 'ghosted' the FTE.

"It's just poof, vanished into thin air."

Cox said she knew nurses who had received verbal offers only to be told the job was no longer available, and had colleagues trying to arrange interviews for roles that were suddenly pulled.

"I've been a nurse for 26 years and I've worked in Australia and the UK and New Zealand, and I've never known it to be as bad as it is right now."

Christchurch Hospital delegate Al Dietschin said where recruitment was happening, it was being "drip-fed".

"When people resign and leave, they're not being replaced."

Many roles that were being advertised on Te Whatu Ora's website a few months ago were quietly taken down, he said.

"They haven't actually been recruited, they've just essentially disappeared."

A registered midwife, whom RNZ agreed not to name, said she had been given orientation documents and told to expect a contract the next week when Te Whatu Ora unexpectedly denied approval for the position.

"Despite severe short staffing there are no jobs advertised in this area.

"My colleagues who work there report having to continually do overtime to make up staff shortages, and unsafe staffing levels.

"This is occurring on maternity wards nation-wide."

According to Health NZ's workforce plan released last year, the country currently needs more than 1000 midwives.

While the nursing workforce has grown by 50 percent since 2000 (to just under 70,000) Te Whatu Ora estimated the shortfall was 4800, with 8000 more needed by 2032.

According to Health NZ, 619 nurses received and accepted offers of employment in June and July.

Chief people officer Andrew Slater said clinical recruitment had continued while budgets were being "finalised".

"Hospital managers and clinical leads are still recruiting for frontline roles, particularly where they need to replace staff.

"Decisions are made at a local level as to which roles should be prioritised."

Ensuring the system had enough doctors, nurses and allied health professionals on the front-line remained "a top priority", he said.

"Health New Zealand is undergoing a reset to ensure we live within our budget and deliver easier and faster access to healthcare for New Zealanders."

-RNZ