Qantas and Jetstar are standing down two thirds of their 30,000 staff as the airlines suspend all international flights from late March due to fallout from the coronavirus outbreak.

"In order to preserve as many jobs as possible longer term, Qantas and Jetstar will stand down the majority of their 30,000 employees until at least the end of May 2020," Qantas said in a statement on Thursday.

Many of Jetstar's New Zealand routes, domestically and internationally, have no seats available after Sunday, its website shows.

E tū's head of aviation Savage said it had 655 members employed by the airlines, including 485 at Qantas and 170 at Jetstar.

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Qantas and its subsidiary Jetstar will suspend all international flights from the end of March.

New Zealand Airline Pilots Association president Andrew Ridling said 212 New Zealand-based pilots were employed by the two airlines - 127 from Qantas and 85 from Jetstar. That's on top 208 New Zealand-based pilots employed by Virgin Australia who would be affected by a Virgin grounding announced on Wednesday.

Earlier this week, cuts to 90 per cent of international flying and about 60 per cent of domestic flying were announced by Qantas and its subsidiary Jetstar but government travel advice made since then had triggered the airlines to go a step further.

With the Australian government now recommending against all overseas travel from Australia, regularly scheduled international flights would continue until late March to assist with repatriation and would then be suspended until at least the end of May 2020, Qantas said.

GETTY About 20,000 Qantas and Jetstar staff will be stood down temporarily.

During the stand down, employees would be able to draw down on annual and long service leave and additional support mechanisms would be introduced, including leave at half pay and early access to long service leave.

Employees with low leave balances at the start of the stand down would be able to access up to four weeks' leave in advance of earning it.

Periods of leave without pay for some employees are inevitable.

Senior group management executives and the board will join the chief executive Alan Joyce and chairman in not being paid until at least the end of the financial year, which ends on June 30.

Annual management bonuses have also been cancelled.

Essential domestic, regional and freight connections would be maintained as much as possible, it said.

Joyce said: "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. This is having a devastating impact on all airlines."

It was in a strong financial position but its wages bill was more than $4 billion a year.

"With the huge drop in revenue we're facing, we have to make difficult decisions to guarantee the future of the national carrier," Joyce said.

"This is a very hard set of circumstances for our people, as it is for lots of parts of the community right now."

The cuts would result in the grounding of 150 aircraft.