Beau Griffin is desperate to get his dodgy knee fixed.

Key points: Darwin hospital patients have had elective surgery cancelled three times in the past 12 months

Darwin hospital patients have had elective surgery cancelled three times in the past 12 months The nurse's union says the overcrowding is exhausting staff and putting patients at risk

The nurse's union says the overcrowding is exhausting staff and putting patients at risk Both levels of government blame each other for the NT health system's lack of capacity

"I'm 29, but I do walk around like I'm 60 sometimes," the Palmerston auto-electrician said.

But as he prepared to go under the knife at Royal Darwin Hospital this week, his operation was cancelled for the third time in the past month.

His elective surgery has been delayed because of a bed blockage at the hospital.

"It's a bloody joke," Mr Griffin said.

"When is it going to be fixed? When am I going to get my surgery?"

"Why is it that as a tax-paying citizen I can't get quality medical care to keep me in the workforce?"

The Top End Health Service says the hospital's 360 beds are over capacity, meaning non-essential operations have been temporarily put on hold.

The Federal and Territory governments spent Thursday blaming each other for problems with the NT's over-stretched health system.

On the ground, the Australian Nursing and Midwifery Federation's local branch secretary Yvonne Falckh said high demand on services was forcing medical staff to work double shifts, causing fatigue and putting patients at risk.

"Whenever you have an environment where staff are working double shifts, extended hours and this is happening repeatedly … patients will always be put at risk," she said.

The head of medical services, Dr Charles Pain, said around six elective surgeries per day have been affected, and it could take another week before those non-urgent operations resume.

Dr Charles Pain said the hospital was working to ensure staff aren't overstretched. ( ABC News: Jano Gibson )

Dr Pain acknowledged staff were being asked to do more, but he insisted safety was not being compromised.

"We are very careful that we don't overstretch our staff in terms of their working hours."

The pressure on beds is being exacerbated by at least two other factors.

Aged care patients continue to occupy more than 30 acute beds because residential facilities outside of the hospital are full.

And mental health patients are being kept in beds within the hospital because more suitable accommodation is also at capacity.

Despite the new Palmerston Regional Hospital — jointly funded by the Commonwealth and Territory budgets — having available beds, Dr Pain said it wasn't a solution to the RDH bed shortage.

"The reason why we can't transfer more patients over there is that it's about appropriateness of where's the best place to manage patients.

Northern Territory Health Minister Natasha Fyles said the Government was looking at ways to expand the range of services available at the Palmerston facility.

But she said increased federal funding was also needed to help move aged care and disability patients out of RDH and into more appropriate care.

"You need to have providers, you need have facilities built and that will be an area of growing need," she said.

"It's wonderful that we have people staying on to retire and having seniors in the Territory so we need to make sure there is the care available."