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."