The WA Health Department has launched an investigation into how COVID-19 jumped between neighbouring rooms in hotel quarantine in Perth.
Genomic testing has shown two sets of couples on the sixth floor of the Mercure Hotel Perth had the same variant of the virus despite arriving from different countries at different times.
In a statement, the WA Health Department confirmed the two new cases, which had previously been reported as being overseas acquired.
"All other guests who previously stayed on the same (sixth) floor during this time and have been released from the hotel facility tested negative prior to release," the statement read.
"These guests will be re-tested and directed to self-isolate until cleared by the public health team."

Motorcycle passenger in critical condition after rider allegedly runs red light in East Rockingham
Two men charged over Australind murder
Last call for donations to support Mandurah's homeless
State Government commits to building $5 million electrical training facility at Rockingham TAFE
McDonald's approved for Dawesville
Wanted man known to frequent Kwinana, Mandurah and Rockingham areas
Mandurah woman completes grueling English Channel swim
Man and child seriously injured in South West crash
Motorists warned to expect delays during Kwinana Freeway upgrades