Qantas and Jetstar will cut international capacity by about 90 per cent, and domestic capacity by around 60 per cent, until at least the end of May.

Qantas said demand for air travel is unlikely to recover for weeks, possibly months.

Qantas said demand for air travel is unlikely to recover for weeks, possibly months. 30,000 employees will be affected and will be managed with a mix of paid and unpaid leave.

30,000 employees will be affected and will be managed with a mix of paid and unpaid leave. The cuts to Qantas and Jetstar routes come on top of previously announced changes to services.

In a statement, the airlines said the changes were due to a drop in travel demand due to coronavirus, and meant grounding about 150 aircraft.

"Despite the deep cuts, the national carrier's critical role in transporting people and goods on key international, domestic, routes will be maintained," the statement read.

"This includes using some domestic passenger aircraft for freight-only flights to replace lost capacity from regular scheduled services."

The airline group said the "precipitous decline in demand" would be unlikely to rebound for weeks or possibly months and the impact would be felt across its entire workforce of 30,000 people.

"The Qantas Group is working to manage this impact as much as possible, including through the use of paid and unpaid leave," the company said in a statement.

The company has introduced a booking waiver for customers who wish to suspend or change their travel plans.

It also said customers with existing bookings on any domestic or international flight until May 31 who no longer want to travel can cancel their flights and get a credit voucher.

The cuts will be phased in from the end of this month and details of the affected routes will be announced in coming days.

Qantas said the cuts to services would come on top of previously announced cuts.

Last week, the airline said it would reduce its capacity by almost a quarter for the next six months due to the "sudden and significant drop" in demand for flights.

Those cuts included grounding 38 aircraft, re-routing London services from Australia through Perth instead of Singapore, and asking staff to take annual leave and unpaid leave.

Qantas CEO Alan Joyce last week said while redundancies were a last resort, the changes meant about 2,000 jobs were now surplus to requirements.

Geoff Thomas from Airlineratings.com said the Government's travel restrictions and fears of COVID-19 would also impact Virgin Australia.

"I see them [Virgin Australia] going to an all-737 fleet, domestically, and I think Qantas will do much the same," he said.

"That will mean lay-offs, I would imagine, for both airlines and [staff taking] leave without pay."

Mr Thomas said the Federal Government should step in to encourage domestic tourism to ensure the airlines' survival.

"We're in unprecedented, unchartered waters with this," he told ABC News.

"This is a very severe shock and that's why it's essential for the Government to have some sort of assistance package, whether it's guarantees for bank loans or whatever's required, because we need these airlines when this is all over."

Deputy Prime Minister and Transport Minister Michael McCormack said the Federal Government was looking at ways to help the nation's airlines get through the coronavirus pandemic.

"We've been asked to look at the fees and charges as far as air services and other things are concerned," he said in Wagga Wagga today.

"We'll be making decisions on that over the next couple of days.

Mr McCormack said steps needed to be taken to avoid an airline folding, although he said Qantas was in a good financial position to weather the storm.

"We absolutely need our airlines to stay viable, and we remember back in 2001 the Ansett collapse, just how terrible this was for regional communities, when we had Kendell Airlines and Hazelton and Ansett have such difficulties at that time."