Public gatherings will be limited to two people in a bid to slow the spread of COVID-19 as the national death toll reaches 16.
Prime Minister Scott Morrison and state and territory leaders on Sunday agreed to further tighten the rule around indoor and outdoor public gatherings from 10 to two.
It will be up to the individual states and territories whether it is strictly enforced by police.
The limit won't apply to members of the same household or family units, Mr Morrison said.
The prime minister on Sunday night also issued new advice relating to who should self-isolate.
He discouraged people aged over 70, people aged over 60 with chronic illness and Indigenous Australians over 50 with chronic illness from leaving home "to the maximum extent practicable".
Mr Morrison said the measure was for the protection of the individuals - who could face more severe effects from the virus - rather than the general public.
"They should limit contact with others as much as possible," he said.
The limit on gatherings at , the maximum is still 10.
"This is not a compulsion, this is strong advice - that people aged 70 and over should stay at home and self-isolate for their own protection to the maximum extent practical.
Recently arrived overseas travellers arrive at the Crown Promenade Hotel in Melbourne for a mandatory 14-day quarantine period. Source: AAP
Mr Morrison said the advice also applied to those aged over 60 with a chronic illness and Indigenous persons over the age of 50."
The group representing older Australians, COTA, said it supported the prime minister's message about vulnerable Australians staying indoors.
"It's not worth the risk [to one's health] to ignore this advice," COTA Australia chief executive Ian Yates said in a statement.
"However, this does not mean that older Australians should shut themselves in their homes and not go outside at all.
"With precautions older people should still walk the dog, or go for a walk by themselves."
As part of new quarantine measures, returning overseas travellers at Sydney International Airport are directed by army officers to board a bus taking them to a hotel. Source: AAP
Two-person rule to be enforced by states, territories
In clarifying the scope of the two-person rule, Mr Morrison said that physical contact should be limited only to household members, which would allow parents to walk together with their children outdoors.
He said it would be up the state and territory authorities to enforce the rule.
"These rules are intended to be instructive, to be a guide, but on this two-person rule, and particularly on the 10, already from memory in South Australia, there is an on-the-spot fine of $1,000 if you violate that rule, so they are not mucking around."
The two-person rule would also apply to shopping centres.
"The strong advice is do not gather in groups. Just don't do it. When you go out shopping, you just go out for what you need, you just do it and go home. It is not a time for browsing.
"It is not a time for catching up with friends or bumping into people and having a long conversation. You can't do that any more."
Freeze on evictions
State and territories will be moving to put on a six-month freeze on evictions of tenants who are unable to meet their financial commitments.
Mr Morrison appealed to landlords to discuss the issue with their tenants.
"We need you to sit down, talk to each other and work this out. Look at businesses which may have a significant reduction in their revenues.
"We want people to sit down and work this out."
Australian Prime Minister Scott Morrison and the Chief Medical Officer Brendan Murphy. Source: AAP
He said further details would be forthcoming on government measures to facilitate "co-operative activity" involving tenants, landlords and the banks.
"There is no rule book for this. We are in uncharted territory but the goal should be shared," he said.
"And that is a business that can reopen on the other side, not weighed down by excessive debts because of rental arrears, a landlord that has a tenant so that they can continue into the future to be able to support the investments that they have made; and banks that have clients, both the landlords and the businesses."
Further work is being done on commercial tenancies.
Early signs of flattening curve
Chief Medical Officer Brendan Murphy says the ramped up measures are "radical".
"Anyone who doesn't need to be out of their home should be in the home. This is radical."
He said while many Australians had so far complied with the lockdown measures, there were cases of people breaching the requirements.
"The science shows that you need more than 90 per cent of the population to be doing it all of the time. So please continue to do what you are doing.
"Continue to follow these rules and hopefully these early signs of flattening will mean that we can keep going and getting a reduction in the rate of increase every day."
Australia has 3,873 cases of COVID-19 and the death toll from the virus stands at 16.
Australians must stay at least 1.5 metres away from others and gatherings are limited to two people unless you are with your family or household.
If you believe you may have contracted the virus, call your doctor (don’t visit) or contact the national Coronavirus Health Information Hotline on 1800 020 080.
If you are struggling to breathe or experiencing a medical emergency, call 000.
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