Western Australian authorities will meet to discuss the discovery of new COVID-19 cases in Queensland and NSW, but no new restrictions have yet been put in place.
Premier Mark McGowan says at this stage both states remain classified very low risk.
"However, any travellers who were at a potential exposure site in those states are required to get tested immediately and self-quarantine," the premier said in a Facebook post.
He said the Emergency Management Committee would meet on Monday afternoon after receiving more information on the new cases.
In Queensland, a doctor at a Brisbane hospital tested positive, and the number of new cases climbed to three on Monday.
While in NSW a worker at a quarantine hotel has become infected, though no new cases have since been found.
The new concerns come as Australia's domestic borders opened fully for the first time since the coronavirus arrived.
People are free to travel across all interstate borders without undergoing quarantine after WA eased restrictions with Victoria overnight.
It is the first time WA has had no quarantine requirements for any state or territory since border restrictions were introduced last April.
All states are now classified as "very low risk" under WA's controlled border system.
But Mr McGowan warned he would not hesitate to bring back a hard border if needed to keep the virus out of WA.
He said his government would continue to be guided by medical advice.
"What you've seen with the Commonwealth government is when necessary, they've shut the border to New Zealand," the premier said.
"The borders work ... they've kept Australia safe and they've kept Western Australia even safer. So if we need to, we'd do it again."
Australian Associated Press
