Prime Minister Scott Morrison announced the ban, which is effective immediately, on Wednesday.

Outdoor gatherings of 500 people or more were banned on the weekend as the federal government tries to curb the spread of the disease.

Airports and public transport facilities including stations, platforms and stops are considered essential.

Medical and health services and emergency service facilities are exempted from the ban, along with disability and aged care centres, which are subject to other restrictions.

Supermarkets, food markets, grocery shops, retail outlets and shopping centres will be allowed to remain open.

Parliaments, jails, courts, factories, construction sites, mines will also be able to continue normal operations.

Major hubs like the Bourke Street Mall and Federation Square in Melbourne and Sydney's Martin Place are also considered essential.

Schools will remain open, with Prime Minister Scott Morrison pointing to Singapore as an example.

"In Singapore they have been quite effective in managing and limiting the transmission of this virus in that country," he told reporters in Canberra on Wednesday.

Chief Medical Officer Brendan Murphy said children had recorded very few instances of severe cases of coronavirus.

"We believe very strongly that it's in the best interests of our children and the nation at this time to keep schools open," he said.

Mr Morrison praised employers who had ensured employees were working from home during the pandemic.

Australian Associated Press