Anyone who flies into Western Australia from coronavirus-stricken Victoria will be immediately tested for COVID-19 when they land and travellers from NSW could be next if the outbreak there worsens.
The WA government last week made tests compulsory for Victorian arrivals on day 11 of their 14-day quarantine period, but will start swabbing as soon as travellers land from Wednesday.
"Now we are adding another layer of caution and safety," Health Minister Roger Cook said on Tuesday.
"We are doubling down on limiting any potential spread of the virus from Victoria.
"We will have staff and resources in place at the airport to take swabs from people before they collect their luggage.
"That means everyone arriving from Victoria will be tested at least twice, the same as we do for our international arrivals."
An interim measure was introduced on Monday, compelling arrivals from Victoria to immediately attend a COVID-19 clinic in the city before going into quarantine.
"This new process is already working well," Mr Cook said.
The state government has also alerted more than 29,000 people who either hold or have applied for a travel exemption that they will need to reapply if they have been to Victoria within the fortnight prior to their planned arrival in WA.
"So we're obviously taking a very tough stance ... we make no apologies for that."
He said NSW was being closely monitored given the cluster linked to the Crossroads Hotel in Sydney's southwest that's linked to 28 cases.
"If they manage to limit the disease outbreak to just that cluster, we potentially won't have to take any further action."
The Australian Nursing Federation has urged against AFL matches going ahead at Optus Stadium later this week, with the venue limited to half-capacity of 30,000.
Geelong will battle Collingwood on Thursday while the derby between Fremantle and the Eagles is on Sunday.
Mr Cook said there were "no guarantees" such a large crowd could prove a bad move but urged those who are unwell to stay away.
One new case was recorded in WA overnight, a 10-year-old boy who arrived in Perth from the UK via Dubai on July 1.
He is the 11th case from that flight.
There are 21 active cases in the state and all are in hotel quarantine.
Australian Associated Press
