The Northern Territory Government has expanded its coronavirus hotspot from seven Sydney suburbs to all of Greater Metropolitan Sydney from midnight tonight.
The declaration followed NSW recording 10 new local coronavirus cases.
Eight cases were also detected in Victoria, linked to a restaurant where a NSW traveller dined on December 21.
NT Health Minister Natasha Fyles said health authorities were looking at developments in metropolitan Melbourne and could soon announce further hotspots given Victoria's new case load.
"Further to this hotspot declaration, we are watching very closely New South Wales and particularly Metropolitan Melbourne," she said.
"We won't hesitate to declare further hotspot regions. I urge all Territorians, please reconsider your travel over the coming weeks."
"This means if you arrive after this time, you will either need to quarantine in Howard Springs facility or in Alice Springs," she said.
"We have seen an outbreak in Sydney, although we've got two specific clusters, we've got a number of cases across Metropolitan Sydney, and that is why the Northern Territory has declared that area a hotspot."
Health authorities yesterday declared Croydon, Croydon Park, Lilli Pilli, Strathfield, Strathfield South, Strathfield North and Sutherland hotspots.
