It came as the ACT recorded its highest ever daily number of cases, with 19 new cases announced on Monday.

ACT chief health officer Dr Kerryn Coleman gave advice to extend the lockdown due to the growing number of cases and exposure sites, including a case in an aged care worker.

Chief Minister Andrew Barr described the ACT outbreak as a "serious situation" and said lockdown was the only way to suppress the virus.

"We do not want to see the numbers continue to grow, we do not want to see exponential growth as we have seen in other jurisdictions," Mr Barr said.

"The best way that we can avoid this is to limit our movement.

"Lockdowns are a proven measure to suppress chains of transmission of the virus."

The ACT will outline any changes to the current lockdown rules on Tuesday. Authorities remained quiet on what those changes may entail.

"We are finalising arrangements for the details of this extension, and will provide a comprehensive set of information for the community for businesses for everyone impacted at [Tuesday's] press conference," Mr Barr said.

Mr Barr said he had informed Prime Minister Scott Morrison about the extended lockdown on Tuesday morning and that economic support would continue for affected businesses.

Education Minister Yvette Berry could outline how remote education will work in the ACT's public schools.

Remote learning for public schools has not yet taken place during this lockdown, after Ms Berry said teachers asked for a week to prepare for remote learning.

The chief minister also indicated the ACT could finish the lockdown earlier than September 2 if the threat subsides.

"We will, of course, continue to assess the situation each and every day. And if we can end the lockdown earlier than the second of September, we will," Mr Barr said.

Four schools have now been affected by Canberra's Covid outbreak. It came after a Lyneham High School student tested positive to the virus. The student attended school between Monday and Thursday last week.

Students from the instrumental music program at the University of Canberra High School in Kaleen have also been affected after a positive case visited the rehearsal room at the school on August 9 between 4pm to 6pm.

In response to the case at Lyneham High School, Ms Berry announced there would be priority testing for staff, students and their families.

On Monday, the Gold Creek pop-up testing centre and the Brindabella Park testing centre set aside dedicated times for people from Lyneham High School.

READ MORE COVID-19 NEWS:

People at the Brindabella testing site who were not from the school were redirected to Queanbeyan's testing site at Seiffert Oval.

Last week a 14-year-old student at Gold Creek School in Nicholls tested positive to the virus. This also affected staff and students at Holy Spirit Catholic School, who were deemed casual contacts.

Police have started to crack down on Canberrans breaching public health orders.

Over the weekend, ACT Policing issued its highest daily number of infringements related to breaches of the territory's public health orders.

On Sunday, there were eight infringements issued.

Of the infringements, six related to a residential construction site in Taylor. The ACT's chief police officer said officers would be looking closely at construction sites.

"We will be doing substantial workplace compliance with WorkSafe ACT in relation to construction sites across the territory to ensure people actually adhere to the health directions and stay at home," Deputy Commissioner Neil Gaughan said.

He said police received 140 complaints from members of the public about compliance on Sunday.

He also said police stopped 1000 cars in the ACT on Sunday as part of compliance activity.

People can be fined $200 for not wearing a face mask. A $1000 fine can be issued for individuals and $8000 for corporations who do not adhere to other public health restrictions.

While Bunnings is deemed an essential retail store and is allowed to stay open, Deputy Commissioner Gaughan said don't hang around or linger at the store, only get what you need and leave.

Our coverage of the health and safety aspects of this outbreak of COVID-19 in the ACT and the lockdown is free for anyone to access. However, we depend on subscription revenue to support our journalism. If you are able, please subscribe here. If you are already a subscriber, thank you for your support. You can also sign up for our newsletters for regular updates.

Our journalists work hard to provide local, up-to-date news to the community. This is how you can continue to access our trusted content: