Support for key domestic networks will continue until the end of January, while regional routes will be propped up until late March.

The government has already spent $150 million helping Qantas, Virgin and smaller airlines survive the coronavirus pandemic.

The upcoming federal budget is expected to contain hundreds of millions of dollars in additional support.

Deputy Prime Minister Michael McCormack said airlines had been smashed by coronavirus shutdowns and border closures.

"The federal government is doing our bit by underwriting these flights to maintain minimum connectivity," he said.

"Now we need the states and territories to do their bit too as we again encourage the continued easing of border restrictions."

Mr McCormack, who is responsible for aviation as infrastructure minister, expects airlines to pass the benefits onto their customers.

"Of course with the subsidies we do expect as a government that airlines will do the right thing and they have, by and large, done the right thing by our regional communities," the minister said.

""But these (subsidies) are to make sure some of those unviable routes, because very few people are travelling, become viable. These are to make sure that we still get those planes in the air at a time when any state premiers are still having border closures.

"I urge and encourage and even implore those premiers to revisit the closures of their borders."

The Transport Workers Union wants any public funding for Qantas conditional on the airline abandoning plans to outsource ground workers, and making the national carrier repay misused JobKeeper wage subsidies.

"Michael McCormack has been very clear today when he said more taxpayers' money would be spent supporting airlines, because planes in the air means jobs on the ground," TWU secretary Michael Kaine said.

"But Qantas is not keeping jobs on the ground, it is axing and outsourcing 2500 workers because it wants to pay workers less for the jobs they do.

"This is a disgraceful waste of public money and Qantas management should get not a cent more unless it agrees to halt the outsourcing."

The Australian Airports Association welcomed the funding extensions but want more money for their struggling sector.

Most regional airports are council-owned and don't have access to JobKeeper payments, with more than 70 per cent of staff placed on reduced hours or made redundant.

Australian Associated Press