The Counties Manukau DHB will extend hours in some departments as part of its response to a staffing crisis at Middlemore hospital.
A letter written by Middlemore's Director of Medicine on behalf of 13 department heads detailed problems in hospital departments.
The letter, to the Health Minister, described a crisis in staffing - in particular causing a delay in cancer treatment - and a lack of beds and facilities.
District health board's acting chief executive Gloria Johnson said they were addressing staff concerns.
This included using side rooms, extending cardiology lab hours, and more allocated theatre time.
Dr Johnson said the board was working with the Crown Monitor and Ministry of Health to deal with the crisis.
The Nurses Organisation said it was shocked by the letter written by clinicians at Middlemore Hospital about delays to cancer treatment.
Written by Director of Medicine Dr Carl Eagleton, the organisation said all departments had concerns and faced challenges in trying to provide high-quality health care.
The letter was released under the Official Information Act to the New Zealand Herald. It was presented to the Minister during his first visit to Middlemore Hospital in early March.
But the organisation said nurses had similar concerns to those expressed by 13 department heads, who described a crisis in staffing.
The issues reported were a symptom of under-investment and were the same in many other hospitals, the Nurses Organisation's chief executive Memo Musa said.
"Across the health sector, nurses are telling us they have inadequate staffing levels to respond to increased needs and an ageing population and the complexity of need they are having to respond to," he said.
Nurses had been rallying to bring attention to staffing levels, he added.
Acting Health Minister Jenny Salesa said the $549 million for DHBs in this year's funding, including an extra $66.2m for Counties Manukau, was not enough to make up for nine years of under-funding.