That positive test left the Westerdam passengers in limbo, but a spokeswoman for HAL confirmed all passengers have now tested negative for COVID-19.

The spokeswoman said the test results "provide the required clearance for remaining guests in Cambodia to begin their onward journey home". More Australians are due to return from Cambodia as soon as Wednesday.

A NSW Health spokeswoman said while the department had been able to contact 20 of those returned passengers by email, all of whom are well and in self isolation, while two more may not have been on the cruise ship at all.

"NSW Health is liaising with the Commonwealth and the cruise ship operator to confirm whether these two people were or were not passengers on the vessel," she said.

Earlier on Wednesday, a spokeswoman for the federal Department of Health said it was providing "direct support" to Australian passengers and crew of the Westerdam, and it was helping states and territories contact all passengers who had returned.

"We urge passengers who have returned to Australia after disembarking the Westerdam to contact the public health unit in their state for advice," she said.

Sandy Smith, from Bli Bli in Queensland, said she and her husband Michael were waiting to hear when they would be booked by Holland America Lines on flights back to Australia.

“We are guessing every day, hopefully it will be today,” she said, adding that more Australians had been booked on flights to return to home on Tuesday night and had left, including Brian and Anne Stock from Brisbane.

“Some Australians have already left and some didn’t wait for HAL [to organise their flights home] but we are waiting because we want to do everything the right way.”

Michael Bellinger, from Tweed Heads, and his wife Rhani were among the ten Australians on board the Westerdam who were left the ship at around noon local time on Wednesday.

The remaining passengers on the Westerdam left Sihanoukville in a convoy of 10 buses to the Sokha Phnom Penh hotel at around noon local time.

As they left the ship after 36 days onboard, Mr Bellinger said he and his wife were "so excited, we have a daughter at home who is so upset".

“We will stay at the hotel until we get our flights out tomorrow or the next day. Holland has been very good, paying for all our flights and reimbursing us [for the cruise].”

Mr Bellinger said passengers had been told they are now able to return home to Australia via Thailand, which had previously stated it would not accept passengers from the Westerdam but wasn’t sure if the couple would return via Thailand, Japan or a third country. There are no direct flights between Cambodia and Australia.

Diamond Princess passengers return to Australia

Meanwhile, up to 180 Australian cruise passengers from the Diamond Princess will be evacuated to Darwin from Japan on Thursday morning and they will be held in a mining camp for a 14-day quarantine period.

More than 540 passengers on that ship tested positive for COVID-19, including 36 Australians.

Minister for Population, Cities and Urban Infrastructure Alan Tudge none of those returning passengers"will board the plane if they have any symptoms of the coronavirus or test positive obviously to the coronavirus".

"The people boarding this flight will actually have five screenings conducted."

The last 36 Australians who were in quarantine on Christmas Island have also boarded flights home.

Of the 15 confirmed cases of COVID-19 in Australia, eight people have fully recovered. Deputy chief medical offier, Professor Paul Kelly said there have been no new cases in Australia for almost two weeks.

"There is no reason why anyone should be concerned about going to areas of our major cities or anywhere elsewhere Chinese people may be living," he said.