Elective surgery has been cancelled at Royal Darwin Hospital, where patients numbers have hit capacity for the second time this year.
A "code yellow" emergency was announced on Wednesday afternoon following what health authorities said was a peak in bed demand.
Category 2 and 3 elective surgeries have been postponed and will be rescheduled.
The department said emergency surgery and specialist outpatient appointments would continue as normal.
The hospital had been at or near capacity for 10 days, according to a statement from the NT Health Department.
"This is despite concentrated efforts from all staff to improve patient flow through admission and discharge initiatives," the statement said.
The statement says a code yellow "indicates an internal or infrastructure emergency" and enacts a number of procedures to manage the demand peak.
Opposition demands plan on overcrowding
On Wednesday afternoon, Health Minister Natasha Fyles said two consecutive long weekends were partly to blame for increased demands on the hospital.
But opposition health spokesman Bill Yan said the peak in demand was not an isolated incident.
"It's worrying that our hospital beds are blocked as COVID-19 has a stranglehold on New South Wales and is affecting Queensland," he said.
In February a code yellow situation lasting about 48 hours was not initially reported by the government.
Overcrowding and capacity problems at the hospital were labelled a "persistent crisis" by the Australian Medical Association in 2018.
