All Australian states and territories have imposed travel restrictions on Sydney.

Starting today, all Australian territories and states have imposed new travel restrictions as a new COVID-19 cluster in the city sparks fears of more transmission.
Sydney is Australia’s most populous city with more than five million people. All Australian states and territories have warned its citizens that they would have to quarantine for 14 days if they decided to travel.
The Australian Capital Territory (ACT) sent out a strict message to Sydney, reading – “Do not come to us”, reports Reuters.
“If you are not an ACT resident and have been in greater Sydney…our message is simple: do not travel to the ACT,”, said the city’s health department.
Starting Monday, residents of Sydney will not be able to visit Victoria, Northern Territory and Queensland. Queensland police intends to reintroduce road check points at the New South Wales (NSW) border to ensure that there is no growth in COVID-19 cases.
South Australia on Sunday imposed a 14-day quarantine period on people coming in from Sydney and banning travellers from affected suburbs. Tasmania on Saturday and the state of Western Australia has closed its borders to prevent the spread of COVID-19.
All other people coming in from New South Wales (NSW) where Sydney is located, will have to prove that they are not coming from the affected regions in Sydney in order to cross state borders.