Crew members from an infected cargo ship could be placed into hotel quarantine in Western Australia as authorities investigate whether local workers were exposed to a coronavirus outbreak aboard a separate vessel.
Ten out of 14 crew members aboard the BBC California have now tested positive since the vessel docked in Fremantle.
All crew members are isolating in separate cabins with their own bathrooms.
Officials are weighing up removing the four healthy crew members from the ship and placing them into hotel quarantine, allowing the infected crew full access to the vessel so it can be prepared for departure as soon as possible.
"We've handled this kind of situation before," Premier Mark McGowan told reporters on Tuesday.
"Our expert team has prepared a plan to put to the BBC California's shipping agent to handle the situation in a manner that protects the health of the crew, the health of the public of Western Australia and ensures the ship can operate safely and sail as soon as practicable."
Mr McGowan said he had been advised the crew members were relatively young and in good health.
He added it was possible the ship would not be able to depart until those who were infected had fully recovered.
The two latest positive cases had not displayed any symptoms prior to being tested as an additional precaution late on Monday.
Serology test results have shown no sign of previous infection among the four healthy crew members.
The vessel left Egypt on June 8 and has since visited three ports in Indonesia. A number of crew members became unwell last week, prompting the ship's captain to seek assistance.
The ship docked at Fremantle Port on Monday, allowing crew members to disembark in small groups so they could be tested inside a shed.
They were met by health workers and police, clad in personal protective equipment, and returned to the ship a short time later.
An outbreak aboard a separate vessel which berthed in Fremantle earlier this month has added to health officials' headaches.
Nine of the 21 crew aboard the Mattina container ship have since tested positive.
The ship, originating from Indonesia, docked in Fremantle from July 10 to 12 and is now in quarantine at the New Zealand port of Bluff.
Twenty-five maritime workers who may have come into contact with the Mattina, including at least four people who boarded the ship, are being contacted and interviewed by WA Health officials to determine their exposure.
"I want to stress that it is standard operating procedure to treat every ship that visits Western Australia as if it may be carrying the virus," Mr McGowan said.
"All workers who have contact with any vessel must wear appropriate PPE, masks and gloves, and take all necessary precautions.
"The chief health officer advises if there is any risk involved with this ship, it is low."
WA has meanwhile reintroduced a 14-day quarantine requirement for travellers from South Australia, which has entered a seven-day lockdown as it deals with a cluster of local cases involving the highly infectious Delta variant.
Mr McGowan warned SA could soon join NSW, Victoria and Queensland in being subject to a hard border.
"I urge any Western Australian that has recently travelled to South Australia to come home immediately," he said.
WA Health is monitoring 17 active cases, including the 10 infected crew members.