Canberra,  Some 50 staff members from Australian flag carrier Qantas and its subsidiary airline, Jetstar, have tested positive for the novel coronavirus, a company official said on Saturday.

The latest cases include eight pilots and 19 crew members, Xinhua news agency quoted the company's medical officer Russell Brown as saying.

Brown said most of those "were from overseas, but they were taking the precautions... wearing masks when flying and being careful".

Qantas medical director Ian Hosegood said in a statement that there was no evidence passengers had caught the virus from infected staff, but could not rule that out.

"In most of these cases, the employees have contracted the coronavirus while overseas including staff who were on holidays," Hosegood said.

"We have put in place increased measures to protect our people while they are at work and our customers including enhanced cleaning at airports and on aircraft and providing necessary safety equipment."

All of the infected employees are under 14 days' quarantine.

The latest figures come amid management's confirmation of a security worker with COVID-19, with the cluster of coronavirus cases at Adelaide Airport continuing to grow.

Twelve Qantas baggage handlers tested positive for the virus, while seven family members have been infected through close contact, it said.

The airline cancelled at least seven Adelaide flights earlier in the week, while state health authorities advised those with COVID-19 symptoms who have been to the airport in the past two weeks, including its car park, to self-isolate and get tested for the virus.