Victorian acting Premier Jacinta Allen on Thursday afternoon announced the state would impose a hard border closure with NSW from 11.59pm Friday.

"This is not an easy choice, closing borders [and] putting in place restrictions is never an easy choice to make," she said. "Certainly not one we wanted to be making and announcing on a day that is supposed to be about celebrating.

"As we have seen throughout the course of 2020, this has been a difficult year with many difficult decisions to make, as a consequence of a virus that causes great damage to the health and well-being of our community."

Victoria's COVID-19 testing commander Jeroen Weimar said the ACT remained a green zone, meaning Canberrans could travel into Victoria after obtaining a border permit.

He confirmed travellers will still be able to drive from the ACT, through NSW to enter the state.

ACT residents will also be able to drive through NSW to get to South Australia, provided they take the most direct route available and do not make any unnecessary stops.

"You can't stop in a township and go for a tour of the town or avail yourself of other facilitates that are not essential to your travel between Queensland and South Australia, or the ACT and South Australia," South Australia Police Commissioner Grant Stevens said.

Canberrans will also be able to fly into South Australia but anyone flying out of Sydney cannot spend more than two hours in the airport and must wear a mask.

Premier Steven Marshall said the border closure to NSW residents would start on Friday in response to the growing COVID-19 outbreak in the state.

South Australians returning from the state and those relocating from NSW will be exempt from the closure, but will still have to quarantine for 14 days. There will also be exemptions for cross-border towns of Wentworth and Broken Hill.

The border closure comes as NSW recorded another 10 new COVID-19 cases, with three linked to a growing cluster in Croydon and five to the northern beaches.

The Northern Territory Health Minister Natasha Fyles announced that from Friday, anyone entering the jurisdiction from greater Sydney will have to undergo mandatory quarantine, either in Howard Springs or Alice Springs.

ACT Chief Health Officer Dr Kerryn Coleman is reminding Canberrans who are celebrating New Year's Eve to remain COVID safe during the festivities. "Similar to Christmas, we know that New Year's Eve is a time of increased social activity, when the community go out and about to meet friends, or host gatherings at their home in the countdown to 2021," Dr Coleman said.

"While there are many people who will be looking to celebrate the back of 2020 with family and friends, COVID-19 has not gone away and we still need to ensure we celebrate the New Year in a COVID safe way.

"As tough as 2020 has been, if we keep following the ACT public health information, we can continue to minimise the risk of COVID-19 and keep our community safe as we head into the New Year."