The Federal Court of Australia is being urged to declare that Qantas is still responsible for paying sick leave to 25,000 workers who have been stood down during the global coronavirus pandemic.

Key points: The national carrier maintains the workers cannot be paid their sick leave because "there is no work to be absent from"

The national carrier maintains the workers cannot be paid their sick leave because "there is no work to be absent from" The Transport Workers' Union has claimed that position cannot be reconciled with the Fair Work Act

The Transport Workers' Union has claimed that position cannot be reconciled with the Fair Work Act A Qantas employee of 35 years has told the court he is not allowed to use his sick leave while he waits for a triple bypass

The application, which was filed in the court's Fair Work Division, marks a rapid escalation in the dispute between the Transport Workers' Union (TWU) and the national carrier, which has taken a battering since domestic and international travel restrictions were put in place.

But Qantas is refusing to budge on the issue and on Tuesday reiterated its long-held stance.

"Unfortunately, the devastating impact that travel restrictions have had on airlines means the majority of our employees are stood down and not receiving their regular income — whether that's normal pay or paid sick leave," a Qantas spokesman told the ABC.

"We know it's a very difficult time for all of our employees.

"Employees who are stood down are not eligible to receive paid sick leave because there is no work for employees to be absent from but they can access annual, long-service leave and other support."

The national carrier's position has infuriated the TWU, which has said that Qantas's position "cannot be accepted".

"If Qantas were correct that an employee has no ordinary hours during a stand-down period, no form of leave would be able to be taken during such a period," the union's lawyer Mark Gibian SC wrote in the submission.

"That is obviously not correct and not a position advanced by Qantas.

"The approach of Qantas cannot be reconciled with the [Fair Work] Act as a whole."

Qantas has been forced to dramatically cut its services as the coronavirus pandemic shut down global travel. ( AAP: Mick Tsikas )

Workers question why they cannot access personal leave

Qantas announced its intention to stand down about two-thirds of its 30,000 strong workforce in late March.

Within days, it had issued a document advising workers that they were not entitled to access paid personal or carer's leave while they were stood down.

One veteran Qantas worker, who has been employed with the national carrier for more than 35 years as a baggage handler in Perth, said he was baffled that he could not access his entitlements while he waited for a triple bypass.

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In a sworn statement, he told the court he was sick "before this coronavirus was even thought of."

"I do not understand why I cannot use my personal leave to continue to cover this period," he said.

"I probably wouldn't be able to get a job at the current time because of my heart condition and because there are so many others without my condition also looking for work.

"I have enough leave accrued."

Another worker, who has been with Qantas for 28 years and is currently fighting cancer, said he could not understand why his entitlements were not being paid during the pandemic.

He said it was putting "significant pressure" on him and his family.

The ABC has previously spoken to a Qantas worker who believed they contracted COVID-19 while working for the airline.

They said they were paid about four days of sick leave before being stood down and losing further access to that leave.

Airline accused of putting costs before workers

The TWU's national secretary, Michael Kaine, called the conduct of Qantas "heartless".

"This is something that should shock the Australian community and not one we'd expect of our national carrier," he said.

"The workers are being frozen out from taking sick leave that is theirs and they've rightly earned," he said.

He accused the national carrier of putting costs before its workers.

"The legislation doesn't work like that. The legislation says that if workers are sick they're entitled to sick leave," he said.

"It's up to Qantas to do what is the right thing to do, and look after workers who have looked after them for decades, in their hour of need."

Mr Kaine said the union was expecting a declaration from the court in a matter of days.