Casual contacts have been told to stay in quarantine rather than join long queues for testing clinics, meaning it could take longer to trace the virus' spread.

The ACT reported 17 new COVID-19 on Tuesday, bringing the total number of cases linked to the current outbreak to 45. Ten of the new cases were linked to known cases.

Thousands of Canberrans have been forced into quarantine, with 7500 close contacts associated with the cases. Casual contacts were told to delay their tests, which could prolong the lockdown if there is a delay in testing.

Late Tuesday, authorities added 10 more close-contact exposure sites were added to the list late on Tuesday night, with almost 2000 primary and secondary students at Harrison and their families to be sent into immediate quarantine.

St Thomas Aquinas Primary School in Charnwood and the Lake Ginninderra College canteen and gym were other education locations added to the growing list.

The number of Canberrans locked in their homes has put pressure on supermarket delivery services, with most booked out for the coming week at least.

The Exhibition Park testing site was also forced to close its gates on Tuesday afternoon after being inundated with hundreds of people wanting a test. Some reported wait times of almost nine hours.

It came after the ACT recorded its highest daily number of tests, with 7380 conducted on Monday.

After high demand on Tuesday morning, ACT Health Minister Rachel Stephen-Smith said casual contacts did not need to join the long queues.

"We are trying to get the messaging out to people that if you know there's a really long queue it is really quite appropriate to wait and go into quarantine, particularly if you're coming to get tested because you've been at one of those casual exposure locations," Ms Stephen-Smith said.

"So we're just asking people to be a little patient and be a little thoughtful about when they come forward for testing."

ACT chief health officer Dr Kerryn Coleman confirmed that community transmission had occurred at six venues.

Dr Coleman said this included the Fiction Club, where there had been six cases of transmission as of Tuesday morning. Canberra's first reported case was a bouncer who worked at the club while infectious.

Other venues with confirmed transmission were Lyneham High School, Gold Creek School, Downer Community Centre, the Assembly pub in Braddon and the Lennock Jaguar Land Rover car dealership in Phillip.

All of these had been deemed as close contact exposure sites.

Dr Coleman said she expected case numbers to fluctuate for at least the next week due to the number of exposure sites.

"What we need to look at over the next two weeks is how many cases appear from those exposure sites that were prior to the lockdown over which we have no control about them appearing as cases," she said.

"So for two weeks from the lockdown date, we will continue to see the fallout or the cases appearing due to those exposures."

New exposure sites identified on Tuesday included the CIT Bruce and Reid campuses and Chapman Primary's after school care building. There were three cases linked to CIT and the positive case from Chapman was a staff member.

Dr Coleman said on Tuesday morning health authorities were confident that 37 of the ACT's cases were linked, including 10 of the 17 cases reported on Tuesday.

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The source of the first COVID-19 case from the outbreak has still not been determined. Genomic sequencing has previously linked it to the Sydney outbreak.

"We are continuing to do investigations in that group of first cases that were identified to see if we can identify any of the linkages that are occurring there," Dr Coleman said.

"My public health priority about that question is making sure that we haven't missed any potential chains of transmission."

There have been no further cases linked to the Greenway Views retirement village, after an aged-care worker tested positive on Monday. Dr Coleman said all residents and staff on-site at the retirement village were tested on Monday.

ACT Chief Minister Andrew Barr also announced adjustments to to Canberra's extended lockdown rules. The lockdown was extended until September 2 on Monday.

Yesterday, Mr Barr said police would ramp up their compliance activity, warning that people should not browse in shops, such as hardware stores, that remain open.

"Regrettably, we need to strengthen our compliance in relation to the essential businesses that remain open," he said.

"In amending our public health directions. We are requiring businesses to take all reasonable steps to ensure that anyone who enters the business gets what they need and leaves promptly.

"ACT Policing will be actively enforcing this in partnership with businesses."

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