A positive case was reported in Goulburn on Tuesday, after a Sydney painter was granted an exemption as an essential worker to attend a construction site at Goulburn Hospital.

Victoria and South Australia have locked out Canberrans, who now require an exemption to enter those states, while travel to Western Australia requires a declaration and 14 days' quarantine on arrival for ACT residents.

ACT residents are currently allowed to travel to Tasmania, the Northern Territory, Queensland and regional NSW without facing quarantine.

ACT residents should minimise interstate travel and be prepared to reconsider their plans at short notice, an ACT government spokeswoman said.

"With COVID-19 cases now in multiple jurisdictions across Australia, people need to be alert and be prepared for the situation to change quickly," she said.

"Canberrans should not be travelling to COVID-19-affected areas.

"If you have recently travelled outside of the ACT, you must check the ACT COVID-19 website regularly and follow the health advice if you have been in any of the exposure locations."

Residents should not travel to greater Sydney, which is under lockdown.

Queensland Premier Annastacia Palaszczuk has left the border with NSW open, saying it is too early to make the call to close it while there are no new locally acquired cases close to the Sunshine State.

She said the Sydney outbreak would be reviewed on a day-to-day basis and the border situation could change at any time.

"We are keeping a very close eye on what's happening in NSW," Ms Palaszczuk said.

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"We are seeing more and more cases. We are seeing more hospitalisations and we are monitoring whether it's spreading to other parts of NSW.

"If we do see it spreading to other parts of NSW, we won't hesitate to shut the border."

It is not clear whether the ACT would be included in any border closure between Queensland and NSW.

In August, Queensland closed the border with both the ACT and NSW, following reports a man used Canberra as a back door to enter Queensland from a Sydney hotspot.

Canberrans were spared from a border closure in December amid the Northern Beaches outbreak in Sydney.

Victoria and South Australia have both defended their decision to shut out ACT residents after ACT Chief Minister Andrew Barr expressed frustration at being lumped in with NSW, as there has not been a locally acquired COVID-19 case in the territory for over a year.

"Through a combination of good management and good luck, we have had very few Covid cases," Mr Barr said last week. "This should be acknowledged by other jurisdictions. I have made this point at national cabinet and bilaterally with almost all other jurisdictions."

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