The NT's Chief Health Officer has declared Greater Brisbane a COVID-19 hotspot, effective immediately.
The hotspot includes the local government areas of Brisbane, Logan, Ipswich, Moreton and Redlands.
Anyone arriving in the NT from these regions must enter mandatory quarantine for 14 days.
This comes after the Queensland government imposed a three day lockdown on Greater Brisbane after a hotel quarantine worker was diagnosed with the more infectious United Kingdom strain of COVID-19.
The worker was in the Greater Brisbane community for five days before being diagnosed.
CHO Hugh Heggie said he wanted to take quick action to stop the virus from getting in to the NT.
"The positive case in Greater Brisbane is the first case of this new highly contagious strain of the virus, outside of quarantine in Australia."
"For this reason, we are taking a cautious approach while we wait and watch what happens across Greater Brisbane over their three-day lockdown period.
The decisions made in the coming days will be critical."
Dr Heggie said people in the NT need to stay vigilant.
"As we have seen happen before things can change quite quickly," he said.
"As I will continue to say, it is important that we all remain vigilant.
"Regularly washing our hands and practicing physical distancing may seem like simple things but they are essential to keeping us safe."
Acting NT Chief Minister Nicole Manison said returned NT residents who have been in the hotspot since January 2 should get tested.
Flights from Brisbane were scheduled to land in Yulara and Darwin today, the passengers have the option of flying back to Queensland or entering quarantine.
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