- According health officials, the man is likely to have contracted the virus during a two-week quarantine stay in a Perth hotel.
- The three-day lockdown begins at midnight on Friday, Western Australia Premier Mark McGowan said.
- "We can't take any chances with the virus," McGowan stressed.
Western Australia's capital of Perth and the neighbouring Peel region will enter a snap three-day lockdown from midnight on Friday after a man tested positive for Covid-19 after emerging from hotel quarantine.
Health officials have said that he is likely to have contracted the virus during a two-week quarantine stay in a Perth hotel, raising concerns about community transmission as more virulent virus strains emerge.
One of his close contacts in Perth has been found to have Covid-19, Western Australia Premier Mark McGowan said in a televised news conference where he announced the lockdown.
"I know this is hard to take and I wish we didn't need to do this. But we can't take any chances with the virus," McGowan said.
The man was in Perth for five days before he flew to Melbourne, where he tested positive. Health authorities in Victoria, of which Melbourne is the capital city, are tracing the 257 passengers onboard flight QF778 from Perth.
"The hotel quarantine system, despite all of its improvements, has to face increasingly complex variants of concern," Victoria state Health Minister Martin Foley said earlier in the day.
McGowan said he has requested the federal government to cut the number of international arrivals per week into Western Australia to 512 from 1 025.
Australia has already tightened its border controls by reducing the number of travellers from India and other virus hotspots.
Having closed its borders more than a year ago, Australia lets mostly citizens and permanent residents return from abroad. Returned travelers, except from New Zealand, have to undergo two weeks of mandatory hotel quarantine at their own expense.
The hotel quarantine system has helped Australia to keep its Covid-19 numbers relatively low compared with other developed countries, with just over 29 500 cases and 910 deaths.