A West Australian man has tested positive to coronavirus after returning from Melbourne but authorities believe it is a historic infection.
The man in his 30s had recently returned to the town of Collie, 200km south of Perth, after spending 14 days in quarantine in Melbourne.
He had travelled back to Australia from Poland.
WA Health on Tuesday said the man had been re-tested upon returning to Collie and returned a "very weak positive result which is sometimes seen in people with old, recovered infections".
He is being re-tested to clarify his infection status and his three closest contacts have been asked to isolate until results are returned.
"WA Health believes the test result most likely reflects an historic infection," the department said in a statement.
"We are asking the community not to panic and to be assured that WA Health will advise the community if results indicate this is an infectious case."
Authorities are continuing to identify areas of concern visited by a COVID-positive hotel security guard and his two housemates.
The state reported no new cases on Tuesday.
But another six public exposure sites, all service stations or fast food outlets in Perth's northern suburbs, were identified by WA Health after further contact tracing and review of CCTV footage.
The guard, aged in his 20s, spent several days in the community after becoming infected while working at the city's Pan Pacific Hotel.
He and his seven housemates, two of whom also tested positive after working as food delivery drivers, were moved into hotel quarantine over the weekend.
WA Health has so far identified 79 close contacts and 49 had tested negative. Results are pending for almost 300 casual contacts.
Premier Mark McGowan said face masks and some restrictions on public gatherings would remain at least until Saturday.
"If we need to extend it, we will announce that later this week," he told reporters.
Wednesday's A-League game between Perth Glory and Melbourne City will be played without a crowd, as happened with last weekend's AFL western derby.
The AFL has allowed Fremantle to switch Sunday's home game against Brisbane to the Gabba, with the return fixture in round 21 shifted to Perth.
It was the "right decision" because the Dockers could not be certain of hosting a crowd, the premier said.
WA has made a $2 million payment to assist with relief efforts in India.
Mr McGowan had led the charge for flights to be paused from the virus-ravaged nation but said the donation was unrelated to backlash against his comments.
"It's about trying to do the right thing in difficult circumstances," he said.
WA will also indefinitely reduce the number of returned Australians it accepts per week after closing three "high-risk" quarantine hotels.
"We all have a great deal of sympathy for any Australians who are overseas, particularly those in COVID hotspots," Mr McGowan said.
Genomic testing has indicated the Pan Pacific guard has the same US variant of the virus as two returned travellers staying on the same floor.
The guests, one who had returned from the US and the other from Indonesia, had arrived on the same plane.
Authorities are yet to determine how the guard became infected.
On his days off work from April 27 to 30, he moved through the community going shopping, seeing friends and visiting Mirrabooka Mosque.
A full list of exposure sites is available on the HealthyWA website.
Restrictions in place in Perth and Peel following a snap three-day lockdown appear to have reduced the risk of a wider outbreak.
Australian Associated Press