Household transmission was responsible for more than two in three of new cases reported on Tuesday, as the territory had a record number of cases.

ACT Chief Minister Andrew Barr announced 30 new cases of the virus on Tuesday. The source of five of those cases is under investigation.

There were 11 cases infectious in the community, 13 were in quarantine for their entire infectious period and the status of six is unknown.

A woman in her 40s, who is not vaccinated, is also in intensive care. Four Canberrans are in hospital with Covid, but only two are being treated for symptoms of the virus.

Of the new cases, 21 caught the virus from a household contact.

Chief health officer Dr Kerryn Coleman said while the number of new cases was higher than previous days it was not unexpected and was due to household transmission.

She said it was concerning but was due to the highly infectious Delta strain, which can take up to 48 hours to show symptoms.

"What we're actually seeing now is our household and close contacts coming up from transmission due to the highly infectious nature of the Delta variant," Dr Coleman said.

"We have seen this pattern in other jurisdictions at the start of these outbreaks as well."

Dr Coleman said numbers would continue to fluctuate.

"We are heading in the right direction," she said.

"We just need to keep doing it for a bit longer."

Mr Barr said it was too early to speculate on whether the rise in case numbers could cause Canberra's lockdown to be extended, the end date is currently set for September 2.

There were two additional cases linked to the disability care cluster on Tuesday, and one associated with the Condamine Court case.

There are now 40 cases associated with the Lyneham High School cluster, 30 linked to the Fiction nightclub and 27 linked to the Southern Cross Basketball stadium.

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Dr Coleman also confirmed transmission had occurred at the Bright Bees Childcare Centre in Nicholls, with three cases associated with the cluster.

There are more than 400 exposure sites across Canberra. In recent days, a number of locations have been listed with exposure times from two weeks ago, including an inner-city construction site and a Girl Guides meeting.

Dr Coleman said health authorities were still investigating how the virus ended up in Canberra.

"We still have a cluster that we're investigating at the very start to see if we can still identify if there are any unidentified chains of transmission that continue to come on the back of that primary cluster," she said.

There are more than 12,400 close contacts in quarantine in Canberra and more than 6100 casual contacts who have self-identified to ACT health authorities.

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