WA has strengthened its border restrictions with Northern Territory, Queensland and the ACT.
From 6pm tonight, those State's will join Victoria on the 'low' risk setting meaning all arrivals will need to complete 14 days of self-quarantine and be tested for COVID-19 on arrival and on day 11.
New South Wales remains at medium risk - with travel not allowed without an exemption.
For now, South Australia and Tasmania will be the only jurisdictions that remain at the ‘very low risk’ setting.
"I know these immediate changes will cause significant disruption for many people, especially with school holidays. But we just cannot afford to take any chances," Premier Mark McGowan said.
"These changes to our border arrangements are a safe and sensible response to the alarming outbreaks we’re seeing over east - and an important step to keep our community safe."
The move comes after WA recorded one new local case of COVID-19 overnight.
The local woman tested positive after returning from a trip to New South Wales.
Phase one restrictions have since been introduced for at least the next three days including mandatory mask wearing.