Australia's fourth-largest city faces prospects of its second snap lockdown in less than a month, officials have warned, after a hotel quarantine security guard in Perth and two of his housemates tested positive for Covid-19.

Western Australia (WA) Premier Mark McGowan said the state's capital city, which last week emerged from a three-day snap lockdown after reporting one Covid-19 infection, was on high alert and a new lockdown was a real prospect.

“I want to avoid going into lockdown again. I know how much it can impact people's lives and businesses but if we need to go back into lockdown we will,” McGowan told reporters, according to Reuters.