All arrivals from overseas will be quarantined in hotels to prevent people flouting the 14-day self-isolation rule.
Prime Minister Scott Morrison said the new rules would apply from midnight Saturday, with arrivals quarantined at their port of arrival, not based on their home state.
ACT Chief Minister Andrew Barr confirmed that the seven passengers arriving on a Qatar Airways flight from Doha to Canberra via Sydney on Saturday would be quarantined in a Canberra hotel - the Burbury in Barton. His spokesperson said that was the final international flight into Canberra.
Mr Morrison said Defence Force and Border Force personnel would be brought in to enforce the new quarantine rules and transport arrivals directly from airports to the hotels.
"I have no doubt the forces will do that in the most sensitive way they can, but it is necessary," he said.
Not only will Defence enforce hotel quarantine, but it would enforce home isolation for people who have already arrived and are supposed to be staying at home for 14 days, Mr Morrison said. Personnel would visit homes and residences of people in isolation and report to the local police whether people were there, he said.
Mr Barr welcomed the offer of Defence Force personnel to ensure compliance with social isolation.
"Right now, the ACT is monitoring hundreds of people that have been asked to self-isolate while they wait for testing, or they are identified as a close contact of a confirmed case," he said.
"Monitoring these contacts will continue to be an onerous task on our local police force, and the offer of help from the ADF will enable the territory to more effectively ensure people are doing the right thing."
International arrivals into Australia are well down on the usual numbers, but thousands are still arriving each day. Mr Morrison said 7120 people had arrived from overseas on Thursday alone.
He was speaking as coronavirus cases in Australia hit 3166. Two weeks ago, on Friday March 13, the number infected was 156. In Italy, the equivalent jump took 10 days rather than 14 days, with Italy recording 155 cases on February 23 and 3089 on March 4.
Chief Medical Officer Brendan Murphy said authorities were worried.
"We are worried about the growth. But as the Prime Minister said, we're in an almost unique situation in this country in that even now a substantial part of the new cases are returned travellers," he said.
"So the Health Protection Principal Committee yesterday recommended to governments that the single most important thing we can do is completely stop the capacity for any returning traveller transmitting the virus."
But Mr Murphy said the biggest concern was the growth in community transmission, which authorities were watching very closely.
"We have to have really good compliance with this social distancing to make it work. We can't have anyone breaking the rules, being stupid, being cavalier, and not taking this seriously," he said. "You have seen what's happened in countries around the world, where big community outbreaks have taken off."
In Sydney, 293 Australians from the Norwegian Jewel cruise ship are already quarantined in the Swissotel, guarded by police.
Late on Friday, the Vasco da Gama was due to arrive in Perth from where the 800 Australians on board were to be taken to Rottnest Island for two weeks' quarantine. Close to 200 passengers from the Ruby Princess, who were allowed to disembark in Sydney on March 19 and make their own way to their home states for two weeks' isolation have tested positive to the coronavirus.
Earlier this week, Mr Murphy called on people to "come down hard" on friends and acquaintances not strictly obeying the self-isolation rules.
Mr Morrison said the government was working on a plan to "hibernate" businesses. He didn't release details, but said everyone would share the burden - including landlords who would lose rent, and local governments that would lose rates and land tax. Banks would also contribute.
"This will be a very innovative approach... The idea is simple - there are businesses which will have to close their doors. They will have to keep them closed either because we have made it necessary for them to do so, or simply there is just not the business to keep their doors open.
"We want those businesses to start again. And we do not want over the course of the next six months or as long as it takes, for those businesses to be so saddled by debt, so saddled by rental payments, so saddled by other liabilities that they will not be able to start again on the other side. We want these businesses to effectively go into a hibernation."
Asked about employee benefits such as long-service leave, Mr Morrison said the government's plan was to keep workers connected to businesses so when things improved they got their jobs back.
"If a tenant, a shop in a local high street somewhere in the country cannot keep their shop open, and they have to put the lock on the door, they can't pay the rent, if the landlord wanted to enforce that on them and kick them out and rip their fit out out and do all that sort of thing, who they think will go into the shop and pay the rent?"
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