Several more Qantas flights, both international and domestic, have been crewed by staff with COVID-19, as questions surround the exemption from the 14-day self-isolation rule for airline crews.

The revelations come as the Transport Workers Union says it lodged notice alleging a breach of workplace safety against the airline on Wednesday.

About 50 Qantas workers – including pilots, cabin crew and baggage handlers – have reportedly tested positive for the coronavirus.

The airline says it is managing the various clusters, and that most cases are from community transmission – including four cabin crew who Qantas says probably caught the virus while in Santiago on an emergency flight to bring Australians home.

On their return to Australia, the cabin crew were exempt from the quarantine imposed to slow the spread of COVID-19.

Since their diagnoses, they have been in self-isolation.

“There’s been no confirmed cases of transmission of the coronavirus to employees or customers on board our aircraft, or any aircraft globally for that matter,” Qantas said.

“That includes instances where someone unwittingly travelled on one of our flights while infected with coronavirus, based on our discussions with health authorities.”

The other concerning cluster is among 17 baggage handlers at Adelaide airport.

Qantas said that was thought to have originated from a worker who returned from an overseas holiday and went back to work with virus symptoms. Their co-workers were also then infected.

There are confirmed coronavirus cases in 17 baggage handlers in Adelaide.

The Transport Workers’ Union says a Qantas worker in Sydney is the latest case among the airline’s staff. Other cases include the baggage handlers in Adelaide, 19 cabin crew and eight pilots.

The union said on Thursday it had requested documents under lawful entry powers from Qantas over breaches of workplace health and safety laws.

“With confirmation of yet another worker infected, people right across the airline will be worried about going home to their families and spreading the infection to them,” TWU NSW Branch Secretary Richard Olsen said.

“We believe that Qantas is in breach of workplace health and safety laws and has not been putting in place systems to minimise the risk.”

Mr Olsen said workers were too scared to speak up.

“At Sydney airport, a worker remains suspended after Qantas took action against him for raising concerns about COVID-19,” he said.

“Now Qantas is being investigated by SafeWork NSW but it shows no sign of changing its tune and putting in place protections for workers.”

Union national secretary Michael Kaine said Qantas had shown a frightening disregard for worker safety since the outbreak of the coronavirus.

“It has operated a business-as-usual response, refusing to hear workers’ concerns about the lack of information, consultation, training and protective gear,” he said.

“Now over 50 Qantas workers have been infected and we believe Qantas has serious questions to answer.”

In other measures in response to the COVID-19 pandemic, Qantas said it now required crew to stay in their hotel rooms if they were overseas between flights.

“We have also advised crew to simply not come to work if they are feeling ill, particularly with early cold or flu-like symptoms,” it said.

In addition, all crew are provided with masks, gloves and other personal protective equipment.