Fears of a coronavirus outbreak in Western Australia are dissipating with no sign of further infections at a Pilbara mine site.
No new cases emerged on Thursday after it was revealed a fly-in, fly-out worker may have been infectious while in the community.
The man in his 30s returned a "very weak" positive test result in recent days but has since tested negative.
He is in isolation and has not displayed any symptoms, having previously tested positive to the virus in March last year after returning from overseas.
The man worked as a maintenance contractor at Fortescue Metal Group's Cloudbreak mine between July 20 and July 27 and went on to attend various sites in Fremantle, Scarborough, Subiaco, South Perth and Greenwood.
More than 1200 PCR tests and 850 rapid antigen tests have been carried out across Fortescue's operations.
"All rapid antigen tests have returned negative results and results are pending for the PCR tests, which are processed in Perth," the company said in a statement to the ASX.
Fortescue said it had suspended some activities but expected to return to full operations later on Thursday, subject to completion of testing.
"It is understood that the contractor has previously had COVID-19 and is not believed to have been infectious during this period," Fortescue said.
Premier Mark McGowan earlier said the man's girlfriend, his housemate and three closest co-workers had all tested negative.
A total of 83 close contacts, the majority from the Cloudbreak mine, have been identified and will be required to quarantine for 14 days.
Contact tracing has so far identified 554 casual contacts who must isolate until they return a negative PCR test result.
A list of exposure sites has grown to 11, including new venues in North Fremantle, South Perth and Greenwood as well as terminals three and four at Perth Airport.
Qantas cancelled eight flights out of Perth on Thursday after a handful of staff were forced to isolate and get tested.
Flights to Newman, Kalgoorlie, Karratha and Port Hedland were among those affected, with passengers set to be re-accommodated.
The infected man had been tested in Perth while preparing to fly to another mine site.
He is believed to have contracted the virus at Perth Airport from a Queensland man who flew there on July 20 and was subsequently denied entry to WA. That man tested positive to the Alpha variant of the virus upon returning to Brisbane.
Mr McGowan said CCTV footage showed the Queensland man, who had been wearing a face mask, walking past the mine worker whose back was turned.
"That's, as far as we're aware, the only interaction between the two of them," he told reporters.
"It's a very, very confusing and odd case because of all these circumstances that are involved."
A seafarer aged in his 30s from the Darya Krishna cargo ship has meanwhile been placed on a ventilator after entering intensive care at Fiona Stanley Hospital last week.
Another crew member is in a stable condition on a respiratory ward, while five cases are recovering aboard the vessel which remains docked in Fremantle.
The BBC California outbreak has been declared over, paving the way for the vessel to depart Fremantle on Saturday after being deep-cleaned.
WA Health is monitoring 10 active cases.
Australian Associated Press