Australia is introducing enforced quarantine by midnight on Saturday for citizens returning home from overseas and will deploy armed forces to ensure people already subjected to self-isolation measures are complying.
Prime Minister Scott Morrison said everyone arriving by plane would be detained in a hotel in the city of their arrival for two weeks, toughening up the previous self-isolation requirements.
Morrison said returning Australians accounted for around two thirds of the country's more than 3,000 coronavirus cases, making it the "biggest issue" to be addressed.
"As time has gone on, the risk of those who are returning from other parts of the world actually increases," Morrison said in a televised briefing.
Australia has already closed its borders to everyone but Australian citizens or residents returning home.
The Australian Defence Force would be deployed to check on people who have already been instructed to self-isolate at their home, Morrison said.
Health officials, meanwhile, stressed that local transmission remains a serious risk and they were keeping an eye on the rate of the increase in cases.
Australia has reported 13 deaths from the pandemic so far.