The ACT has reported 13 new COVID-19 cases in the 24 hours to 8pm on Tuesday.

Eight cases were linked to existing cases and outbreaks, with the remaining cases under investigation.

Five cases were in quarantine for their full infectious period, while eight were infectious in the community for at least part of their infectious period.

There are seven people in hospital with the virus and one is in intensive care.

There were 3300 tests taken on Tuesday and there were 4000 vaccines administered at ACT government clinics.

Chief Minister Andrew Barr said he expected the the territory would pass the 75 per cent fully vaccinated threshold for the population over 12.

On Tuesday, the ACT's lockdown was extended for an extra four weeks until October 15.

Mr Barr provided some details about what restrictions would be gradually eased after lockdown finished, after he was criticised for providing a lack of detail on Tuesday.

"When looking to change our public health restrictions, we will consider those national and local vaccination rates, the levels of community transmission, especially the proportion of cases infectious in the community, our testing rates and our testing turnaround time so that we can quickly isolate positive cases," he said.

"We expect restrictions to gradually change as we transition through these vaccination phases in October and November, with the caveat that they may need to be adjusted to respond to increased risk of COVID-19.

Mr Barr said the types of restrictions that would be changed included household visitor numbers, outdoor gathering sizes would increase and density restrictions would start at one person per-four-square metres and go up to one person per-two-square-metres.

But he said it would not be possible to give advance notice of exact restrictions at present given further work needed to be worked through in the national plan and it depended on the nature of Canberra's outbreak.

"Challenging to communicate this level of detail this far in advance," Mr Barr said.

He said the public could expect notice about one week in advance.

Mr Barr said he wanted the community to work towards a safe and happy Christmas but warned that the city would face some difficult times ahead.

"This is one of the toughest moments in our city's history," he said.

Deputy chief health officer Dr Vanessa Johnston said if restrictions were relaxed now the virus would escalate rapidly through the community.

"This is why our social restrictions are so important to stop the spread of the virus," she said.

"While we're working towards our vaccination goals. We continue to have over 50 cases with unknown sources of transmission. This means there are cases of COVID-19 in the community that we are not aware of."

Part of the reason for the extension was due to a rapid growth in the number of mystery cases in recent weeks.

There have been 53 cases in the territory's outbreak where the source of the infection is unknown. Twenty-eight of these cases had been identified in the past two weeks.

Minor changes will come into effect from 11.59pm on Friday. These include allowing real estate agents to conduct in-person viewings of properties by appointment, recreational sport for five people and small businesses to have five people on site to operate click-and-collect services.

More to come.