More than a quarter of patients rushed to Auckland City Hospital's emergency room are waiting over six hours to be seen.

The stretched delays mark a breach in Ministry of Health targets for limiting wait times.

In April, less than 73 per cent of patients were being seen within the six hours, ADHB's June Hospital Advisory Committee agenda revealed.

Every day around 210 people were turning up to Auckland Hospital's ED, putting "significant pressure" on the services, the agenda showed.

Since May, the report said adult and children emergency departments had struggled to manage seeing 95 per cent of patients within the six-hour limit.

Two areas of "significant concern" were radiology, accessing MRIs, and radiation oncology - both services impacting patients with multiple tumours.

The report said this strain was a result of seasonal capacity rather than ongoing issues within services. But Lung services continued to be impacted adversely.

This comes at a time when Middlemore Hospital is also bursting at the seams.

A letter from health bosses at Middlemore Hospital to Health Minister David Clark revealed shocking fears including cancers being discovered too late and poorer patients being overlooked.

On behalf of department heads, the Counties Manukau DHB director of medicine wrote that the general medicine department was in crisis, with fears that the hospital wouldn't cope with a surge in flu cases.

The four DHBs that make up the northern region – Northland, Waitemata, Auckland and Counties Manukau – have made a case for a new hospital in their Northern Region Long Term Investment Plan.

Health Minister David Clark said last month that the Government was aware of the pressures on Auckland hospital services that come with a growing and ageing population.

"But that does not necessarily require a new hospital.

"Over time we will increase hospital capacity in Auckland, that's one reason why the Government pumped $750 million into capital investment in health in the Budget," he said.

In May, Auckland Hospital opened a new unit in a bid to reduce these numbers. The June report said winter-planning was underway and early recruitment was taking place.

Wait times for May are yet to be released.