Transport Workers Union national secretary Michael Kaine said Qantas was forcing its workforce to bail it out, by standing them down and seizing future leave balances that were yet to be accrued.
"It means when the airline returns to profitability, its share price will soar and executives will return to massive bonuses on the back of workers sacrificing their entitlements," he said.
"The Qantas announcement today amounts to workers bailing out the airline."
Qantas responded to the statement, saying, if airlines kept paying workers when there was no work there would not be any airlines left to employ their members.
"The coronavirus is the biggest crisis to ever face global aviation, and the TWU would rather criticise the company and grandstand than work with us to weather the storm," a Qantas spokeswoman said.