Doctors say Canberra's worsening emergency department wait times are due to insufficient beds and infrastructure across all of Canberra Hospital.
The latest quarterly report on ACT's public hospitals showed their performance hit a new low with fewer patients getting timely treatment in emergency departments.
Health Minister Rachel Stephen Smith acknowledged times should be better but said Canberra Hospital performed on par with other hospitals its size.
"It's very easy to make comparisons between the ACT and other jurisdictions. But the ACT doesn't have the same patient population as other jurisdictions," she said.
"ACT health services treat not only ACT residents but we treat the sickest residents from our region in southern NSW.
"We have a much higher level of need in the patient population and that does impact on the performance of our system.
"We also need to remember that while this is a report of the whole ACT health service, Canberra Hospital and Calvary, Canberra Hospital is the main hospital in the ACT and compared to its peers, like to like, it actually performs on par with its peer hospitals around the country.
"Having said that, of course we are not happy with where we are at in terms of our emergency department wait times."
She said work to expand Calvary Hospital's emergency department would be under way soon, while the $500-million SPIRE expansion - due to open in 2024 - would service the needs of the territory into the next decade.
The most recent data from the Australian Institute of Health and Welfare showed while Canberra Hospital performed on par with its peers for treatment times of category two patients, it was among the worst performing for category three to five patients.
Australian Medical Association ACT president Antonio Di Dio said ACT's performance was disappointing and had been for a long time.
"The usual reasons are apparent - insufficient inpatient beds to get patients out of the emergency department and into the hospital," he said.
"Significant parts of Canberra Hospital are overdue for replacement and an expansion of capacity is needed."
He said short term fixes that created extra space in the emergency departments only postponed the real problem of being able to get patients out of the ED and into the hospital's wards.
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Dr Di Dio said the large investment in walk in centres - about $54 million since they opened - could be used in more innovative ways like incentivising GPs to treat patients after hours or more beds in hospitals.
Acting opposition spokesman for health Andrew Wall said work to expand Canberra Hospital should have started a long time ago.
"It doesn't matter how you cut it, the ACT health system under Labor is putting patient safety at risk and the government's failure to invest in infrastructure is putting the Canberra community at risk through inadequate health services.