All travellers coming into Australia will need to self-isolate for 14 days, as the Morrison government escalates its response to the coronavirus outbreak.
Cruise ships will also be banned from docking in Australia for at least 30 days, Prime Minister Scott Morrison said after a meeting of the new National Cabinet on Sunday.
Mr Morrison said the new measures - which come into effect from midnight on Sunday - would help "flatten the curve" and slow the spread of the virus.
There are now 250 cases of COVID-19 in Australia.
Deputy chief medical officer Professor Paul Kelly said while the number may seem low, it was high compared to this time a week ago, with increasing community transmission.
"The next proportional step to take [is] to decrease those travel-related illnesses," Dr Kelly said.
It would be an offence under state and territory law to break self-isolation within two weeks of entering the country, with Australians encouraged to police each other.
"The states and territories wisely are not going to create event police or social distancing police or things of that nature. That would not be a wise use of police resources around the country but legislation would mean that if a person did fail to observe the 14 days self isolation or if an event was organised it would be contrary - once those provisions are put in place - to state law," Mr Morrison said.
"If your mate has been to Bali and they come back and they turn up at work and they are sitting next to you, they will be committing an offence, so I think it's up to all of us that we are ensuring [the quarantine] is in place."
It comes after New Zealand Prime Minister Jacinda Ardern announced a similar mandatory mass quarantine for people entering the country.
Australia will also extend its "social distancing" measures to combat the spread of the virus.
"No more handshakes. That is a new thing we've moved to, something I will be practising," Mr Morrison said.
Federal cabinet will meet via video-conference, instead of all the members being in one place, while politicians will curb travel.
A question mark still hangs over whether federal parliament will sit Monday week.
Mr Morrison said he was in discussions with Opposition Leader Anthony Albanese, as well as Speaker Tony Smith and Senate President Scott Ryan about what would happen.
The ban on events with more than 500 people coming into effect on Monday will still proceed, with further restrictions on the cards in the coming weeks and months.
States and territories could also move to a state of emergency to deal with the public health crisis.
However Mr Morrison said there were no plans to lock down schools, universities or public transport at this stage.
Mr Morrison said the international medical advice was that it was counterintuitive to close schools as it meant children were in increased contact with members of the broader community, and it also prevented critical workers such as nurses or doctors from being able to attend work as they had to care for their children.
"[Closing schools] could make the situation worse, not better," Mr Morrison said.
Earlier, Chief Medical Officer Professor Brendan Murphy said people could still go to the movies or to the gym, so long as they practiced good hygiene.
"The move to reduce mass gatherings is a pre-emptive move.
"If you're going to the gym I would be very focused on hand washing, using hand sanitisers, all of those social distancing, good hygiene measures."
Professor Murphy said while they were not telling people to stop taking public transport, this could change as the number of cases rose.
However he warned people over 70 to be more careful - especially if they had a chronic disease.
"Well, I think if you're over 70 and you've got chronic disease, at the moment the risk is very low but you might want to start thinking about taking more social distancing measures in the future," Professor Murphy said.
Mr Morrison said while the changes would be disruptive, he hoped Australians would not lose "our sense of Australianess in all of this" and continue to support one another.
"If you have someone in self-isolation, an elderly person next to you or down the road, they will be wisely exercising greater precautions about their social interactions - make them a casserole and leave it at the door," Mr Morrison said.
"Be good to each other."
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