Authorities are searching for people who came in contact with an Australian Defence Force member with coronavirus who flew in and out of Canberra for a meeting last month.
Defence is also ordering all personnel and staff who present with cold or flu-like symptoms to stay away from work and get tested for COVID-19.
It comes as the number of Australians with the virus continues to rise, and as it claimed its third life - an 82-year-old man who acquired it from a worker in his Sydney aged care home.
Defence has said the member who came to Canberra was a man in his 40s, and one of two defence personnel who had been confirmed to have contracted the virus.
The second affected defence force member was also a NSW resident, health authorities have confirmed, although there is some confusion about whether he or she was also at the meeting. Defence has indicated in a statement that they were, but ACT Health believes they had not been in the territory. It is also unclear when this second person was diagnosed.
ACT Health said there were no confirmed cases of coronavirus in the ACT as of 1pm on Sunday.
It said the man in his 40s had travelled on flights between Sydney and Canberra on February 28 for a meeting at defence's headquarters in Russell while he may have been infectious with the virus.
The flights were Qantas flight QF1509 between Sydney and Canberra departing at 6.45am and Virgin flight VA651 between Canberra and Sydney leaving at 2.35pm.
ACT Health is asking anyone seated in rows two to six on the first flight and rows three to seven on the second flight to self-isolate and contact the Centre for Disease Control.
"Anyone else travelling on these flights in other rows are not considered to be close contacts and should monitor their health until March 13," an ACT Health spokesman said.
The man onboard the flight, who later tested positive to coronavirus, was a known close contact of a previously confirmed case.
Virgin Australia said it had been notified and had provided the passenger manifest to NSW Health. The crew of the operating aircraft had been contacted and the aircraft "is undergoing additional cleaning".
Qantas was contacted but was unable to provide any clarity as to its arrangements.
The man was officially diagnosed with coronavirus on Saturday night, but said he had reported feeling symptoms on the day of the two flights.
The man travelled by private car to and from the meeting and did not have any other exposure with people while he was in Canberra.
Health and defence authorities are working to contact people who were on the flight or at the meeting.
He was one of two new cases of confirmed coronavirus in Australia on Sunday, bringing the total number to 70.
In a statement, Chief of Defence Force Angus Campbell and department secretary Greg Moriarty said the two personnel who had tested positive to the virus had been isolated.
"Efforts to trace any contact are focused on the two officers travelling to a meeting at Defence Headquarters, Russell, ACT on 28 February 2020," they said.
"Defence is cooperating with NSW and ACT Health authorities to contact, isolate, test and support persons involved.
"As a necessary precautionary measure to address the increasing risk of COVID-19 infection within Defence and the general community, any Defence personnel and those working in Defence establishments who present with cold/flu like symptoms will remove themselves from the workplace and arrange with their local health centre or GP for testing for COVID-19."
ACT chief health officer Dr Kerryn Coleman said health authorities were in the process of contacting people who may have come into contact with the man on the plane.
"I can totally understand the community may be concerned, and we're working as hard as we can to identify the movements of the person to make sure we have the most accurate information," Dr Coleman said.
"For people in the other rows of those planes, there is minimal risk of exposure."
ACT Health said 270 people had been tested for the virus in Canberra, all recording negative results.
As of 9am on Sunday, 36 coronavirus cases were recorded in NSW, 11 in Queensland and six in South Australia. Of the 63 cases of coronavirus in Australia, 22 of them have been reported to have recovered. There have been three deaths, including an 82-year-old NSW man who died on Sunday after contracting coronavirus in his Sydney aged care home from an infected worker at BaptistCare's Dorothy Henderson Lodge in Macquarie Park.
Travel bans have been put in place for virus hot spots including China, Iran and South Korea.
Federal Health Minister Greg Hunt said on Sunday more than 10,000 people had been tested for the virus in Australia.
"We have a testing regime which is the equal of any in the world," Mr Hunt said.
Canberra residents who think they are developing symptoms of coronavirus have been urged to contact their GP for assessment and testing.
Deputy national chief medical officer Professor Paul Kelly on Saturday said it was not surprising the ACT had not recorded any confirmed cases as of yet.
"There is a lot of international travel through and to the ACT, but generally not directly. So people found on the border at the place of first stepping on Australian soil are likely to be diagnosed there rather than the ACT at the moment," he said.
The federal government is reportedly finalising a $5 billion stimulus package amid the outbreak including reducing deeming rates for pensioners, providing local councils with funding and expanding business instant asset write-offs.