An effective travel ban in the Australian Capital Territory for those from Greater Sydney, Wollongong, and the Central Coast has been extended to January 6.
It will mean those separated by the restrictions over Christmas will have to remain apart for another week.
The restrictions were announced on December 20, while Canberrans returning home from those places were told they would have to quarantine for 14 days upon their arrival.
ACT Chief Health Officer Kerryn Coleman said they would review the situation on January 5.
It comes after NSW Premier Gladys Berejiklian this morning announced restrictions would be tightened in parts of the state.
There were 18 new cases in Sydney in the past 24 hours, including nine in the northern beaches and six in a new cluster in Croydon.
'We know that it can change quickly': Travel discouraged in NSW
Dr Coleman said she had made the decision to extend the restrictions based on the continued presence of COVID-19 cases that could not be traced in NSW.
There were no new cases of the virus detected in the territory in the last 24 hours, but she said the risk remained high.
"We have unfortunately continued to see new exposure locations and community transmission occurring outside of the northern beaches location," Dr Coleman said.
"This continues to pose a risk to the ACT community.
"We have fought so hard to be in a fantastic position in the ACT and we want to continue that."
Dr Coleman said the fact that people would have travelled and gathered with friends and family more than usual over the past week meant the risk was even higher.
ACT residents returning home from those regions in NSW must also notify authorities of their intention, ahead of travelling, using an online declaration form.
"I am also reminding Canberrans not to travel to Greater Sydney or any other COVID-19-affected area and to reconsider travel to NSW more broadly at this time," she said.
"We are keeping a very close watch on the situation in NSW, but we know that it can change quickly.
"I know — we know — that the outbreak in NSW has affected many holiday plans, but with new affected locations being identified daily, please reconsider your need to travel at this point in time."
Canberrans encouraged to dine out, but without fireworks
New Year's Eve was already predicted to be a little subdued in the capital.
For the second year in a row, there will be no fireworks display in the ACT, after bushfires and heavy smoke put paid to the event at the close of 2019.
Instead, the ACT Government is spreading out the festivities to the suburbs.
Local musicians will play in various locations while buildings such as the Royal Australian Mint and National Carillon will be lit up to mark the occasion.
Canberrans are also being encouraged to dine out to support local businesses.
Chief Minister Andrew Barr said Canberrans who had been hoping for an "emotional release" at New Year would be disappointed.
"Our greatest risk is complacency, and people taking for granted that the virus can't spread rapidly," Mr Barr said.
"I guess if I had one message for everyone, it's that 2021 is going to be like 2020.
"Maybe towards the end of 2021 with a successful vaccine roll-out, things will look different."
