The man in his 40s tested positive to the virus on Saturday after returning from overseas where he did not have to undertake a 14-day quarantine in a hotel and was able to drive to his Canberra home.

"He traveled back to Canberra extremely safely in a private car, and no one else was exposed in that trip," Chief Health Officer Dr Kerryn Coleman said.

His family has since been exposed to the virus, she said and are now in quarantine until health authorities allow them to leave.

Diplomats, airline and boat crew, excluding cruise ships, are the few groups exempt from the otherwise mandatory 14-day hotel quarantine for all returning travellers.

Australia has legal requirements under the Vienna Convention to allow diplomats freedom of movement and travel and protection from detention. Diplomats are not required to isolate in a hotel but are advised to do so at home.

There are currently 20 foreign diplomats and their families self-isolating.

Federal Health Minister Greg Hunt said the case would be reviewed by the expert medical panel, which was examining the origin of all cases now.

He said if the panel recommended changes to the self-exemption policy, the government would adopt them.

Mr Hunt also said any breach would be taken up with a diplomat's home country "very strongly".

"Australian or non-Australian. If they have their feet on Australian soil, they will be expected to adopt the rules," he said.

Chief Minister Andrew Barr said diplomats were in a different category to other travelers and acknowledged the Department of Foreign Affairs and Trade had to follow international protocol.

"Diplomatic immunity is obviously immunity from certain things but not from COVID-19," he said.

He said the greatest risk for Australia right now was someone contracting the virus overseas and bringing it to our shores, as thousands of Australians are being repatriated and Canberra receiving a flight from Nepal on Tuesday.

"In this circumstance the diplomat did follow the clear health advice which makes this outcome less worse than it could have been," he said.

Dr Coleman was confident the case was not a broader risk to the community.

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There have been 108 coronavirus cases in the ACT and more than 20,000 negative tests have been returned.

There is one active case, 104 people have recovered and three people have died in the ACT.

Dr Coleman expected more cases would be found in the ACT as restrictions ease and travel is allowed.

"It is likely that cases will continue to be diagnosed around Australia, including in the ACT," she said.

"The ACT will continue to have a strong and rapid public health response to any new cases."