Premier Mark McGowan has confirmed six people quarantined at the Hotel Grand Chancellor in Brisbane before returning to Western Australia.
The Queensland hotel quarantine facility has been evacuated after testing found six cases linked to the highly contagious UK strain of COVID-19.
Mr McGowan said the six returned travellers who stayed at the hotel were all in home quarantine in WA.
"They've all been tested, I am advised, and returned a negative test," he said.
"They are all in home quarantine and their close contacts are being monitored on a daily basis.
"They'll be further tested as time goes by."
Health Minister Roger Cook said the six people were ordered to home quarantine for 14 days from their arrival "as a precaution".
"The risk is very low," Mr Cook said.
"It was one floor in that particular hotel, and although we can't identify how it moved from one room to another on that same floor, it is at this point a very low risk."
Mr Cook said Queensland authorities were exploring whether the air conditioning system, or the fact the hotel was an older building, played any role in the spread.
"We don't have any concerns about the air conditioning systems in our hotels," Mr Cook said.
Mr McGowan said he spoke to Queensland Premier Annastacia Palaszczuk this morning about the Brisbane cluster.
"The Grand Chancellor event … is inexplicable, what has occurred there," he said.
"And shows that the British strain of the virus is very, very concerning and very, very worrying for everyone. We don't want it to get out into the community."
Longer quarantine stays for infected patients
The WA Government will now require anyone who tests positive for COVID-19 in hotel quarantine to stay in the system for a longer period of time after receiving their positive result.
Previously, people had been required to stay in hotel quarantine for ten days after their diagnosis but that requirement has been extended to 14 days.
Mr Cook said while the state's quarantine system was adequate, the measure would offer additional protection against the variant UK strain of the virus.
"The new UK strain is obviously providing extra challenges for everyone globally, health systems globally," Mr Cook said.
"We are continuing to learn from other jurisdictions about what are the best ways to manage it and to date we're making some changes as we move forward."
McGowan calls for quarantine rethink
WA has recorded two new cases of COVID-19 in hotel quarantine.
Mr McGowan repeated his calls for the Federal Government to consider sending international arrivals to remote federally run facilities such as Christmas Island, amid growing concerns over the mutant UK strain.
The Commonwealth last year rejected the Premier's suggestion but he said it was time to reconsider.
"We need to constantly review and constantly update," he said.
"I am more than happy to have another conversation with the Federal Government about the use of remote Commonwealth facilities because those facilities are there, and they are available, and there are experienced staff that can deal with these matters."
WA Opposition leader Zak Kirkup said he "wholeheartedly" supported the state's hotel quarantine system, amid the problems being faced in Queensland.
"I am very confident that if the Chief Health Officer (Dr Andrew Robertson) is saying our hotel quarantine system is the right one, that is the one we support, absolutely," Mr Kirkup said.