ACT residents will be required to wear face masks if COVID-19 cases are detected in Canberra or the immediate surrounding region, Chief Minister Andrew Barr announced on Sunday.
It comes as NSW Premier Gladys Berejiklian strongly recommended masks be worn in areas where social distancing could not be guaranteed, in places of worship, in areas of high case numbers and for customer facing workers.
Chief Minister Andrew Barr said the risk of coronavirus returning to the ACT was edging higher as the active number of cases across NSW increased.
"Canberra is not an area of high community transmission and, therefore, the wearing of face masks is not currently a mandatory requirement," Mr Barr said.
"However, a situation may arise in the future where that changes. If we start to see cases in areas immediately surrounding the ACT, or we start to get new cases in Canberra, then wearing a face mask in public will feature as part of our response."
Mr Barr said masks would be the fourth line of defence in addition to physical distancing, good hygiene practices and staying home if you are unwell.
"ACT residents, particularly those unable to physically distance in their daily work or daily activities, are now encouraged to prepare for a time where wearing a face mask becomes another part of how we respond to the threat of COVID-19," Mr Barr said.
Mr Barr reiterated the advice that Canberrans should not travel to the Greater Sydney area unless absolutely necessary and said now was not the time to invite family or friends from Sydney to Canberra.
He said any travel outside the ACT should be carefully considered and any Canberrans visiting NSW should follow NSW recommendations about masks in any of the four scenarios where they are encouraged.
It comes as Victorian premier Daniel Andrews declared a state of disaster for the state, and introduced stage four restrictions across metropolitan Melbourne, including an 8pm curfew.
While the ACT government hasn't made wearing masks mandatory, the call from Woolworths asking shoppers in the ACT, NSW and parts of Queensland to wear a mask comes into affect on Monday.