A Darwin man, 52, has COVID-19, becoming the first confirmed case in the Northern Territory, as authorities try to prevent outbreaks in indigenous communities.

Health authorities say they are concerned about the coronavirus spreading to remote indigenous communities where it will be difficult to control as the Northern Territory confirmed its first case.

A 52-year-old Sydney man who flew into Darwin on a Qantas flight at lunchtime on Tuesday has tested positive, deputy Chief Health Officer Dianne Stephens says.

After landing, he discovered that a person he had recently travelled overseas with had tested positive for COVID-19.

He visited a Woolworths supermarket in Darwin's CBD but says he had no other interactions in the community.

"He felt a little unwell, he immediately isolated himself and rang a GP," Professor Stephens said.

"After the test results were confirmed, he moved from the hotel (on Wednesday evening) to hospital, in isolation at Royal Darwin Hospital and all appropriate public health measures were taken."

The man would almost certainly have contracted the virus overseas with his travelling companion, she said.

People sitting within two rows of the man on the plane were being contacted, she said, but anyone on flight QF840 who felt unwell should also get tested if they have symptoms.

A remote health pandemic plan was being finalised amid concerns the virus could spread quickly in indigenous communities, Prof Stephens said.

The federal government has set up an indigenous advisory committee to respond to the coronavirus.

Some remote communities such as the APY lands in South Australia near the border with the NT have asked to block visitors during the outbreak.

"We are particularly concerned about the remote situation and taking active measures to mitigate the risk," Prof Stephens said.

"Our indigenous population do have a higher health chronic disease burden; people who are elderly or do have a chronic disease are more at risk of getting severe disease with COVID-19 infection.

"So that's why we are particularly concerned about our remote communities.

"Also the overcrowded housing in remote communities means it is easier for the virus to be spread between community members."

Health authorities are working with indigenous communities to institute "social distancing" to separate people if needed, safe places for quarantine, and working out how to most efficiently get tests from remote areas to Darwin.

Darwin has only one main hospital plus a smaller regional hospital in Palmerston, so if there were a large coronavirus outbreak there is capacity to expand those, plus use other facilities such as defence bases or the National Critical Care and Trauma Response Centre.