Qantas said all of its international flights would be suspended by late March for at least two months after the government told citizens Wednesday to forego all overseas travel in a bid to halt the spread of novel coronavirus.

"The efforts to contain the spread of coronavirus have led to a huge drop in travel demand, the likes of which we have never seen before," Qantas chief executive Alan Joyce said, adding that the airline would suspend 20,000 of its 30,000 staff during the shutdown.

The move also affected Qantas' budget offshoot, Jetstar. A number of foreign airlines also service Australian routes.

Qantas announced earlier this week a 90 percent cut in overseas flights while Virgin Australia grounded its entire international fleet.

Qantas is maintaining 60 percent of its domestic flights and Virgin Australia 50 percent.

Australia has reported more than 700 confirmed cases of coronavirus, with the increase in infections accelerating daily. There have been six deaths.

Officials say the majority of new cases involve people arriving from overseas or those who have been in contact with them.

On Wednesday, Prime Minister Scott Morrison announced an unprecedented decision to advise all Australians to forego foreign travel.

He has also ordered a halt to all cruise ship activity into and out of the country, banned outdoor gatherings of more than 500 people and indoor groups of more than 100.

But he stopped short of ordering the kind of lockdown seen in some pandemic hotspots or closing the nation's schools.

Meanwhile, the island state of Tasmania announced Thursday than any non-essential travellers arriving in the island from Saturday would have to self-quarantine for 14 days.

The move, the first by any Australian state to restrict domestic travel, excludes health workers and essential personnel dealing with trade.

Tasmania, off Australia's southern coast, has a population of around 500,000 and has reported just 10 cases of coronavirus.