Australians returning to the country to be sent to quarantine facilities for two weeks.

Thousands of Australians returning to the country will be quarantined in hotels and other accommodation facilities for two weeks before being allowed to go home, under new measures to control the spread of coronavirus.

Mr Morrison said two-thirds of the nation's confirmed cases of coronavirus had come from people travelling from overseas. 

All passengers who arrive in Australia after midnight on Saturday will go into mandatory quarantine in hotels for a fortnight, Prime Minister Scott Morrison has announced.

"If their home is in South Australia or in Perth or in Tasmania and they have arrived in Melbourne, they will be quarantining in Melbourne. If it's in Sydney, it will be if Sydney. If it's Brisbane, and so on," Mr Morrison said.

Mr Morrison said the cost of the quarantining travellers in hotels and other facilities will be borne by the states and territories, with NSW expected to be the most affected. 

On Thursday, more than 7,000 people landed at Australian Airports from overseas. 

Defence Force personnel will be brought in to support state and territory police in enforcing the mandatory quarantine and the self-isolation rules that apply to people who are already in Australia or who arrive before the Saturday midnight deadline.