Thousands of passengers who sailed on the last two voyages of the stricken Ruby Princess cruise ship will be questioned, as NSW Police investigate the massive coronavirus outbreak linked to the vessel.

Key points: The survey will ask passengers about their health and what took place on their Ruby Princes cruise

The survey will ask passengers about their health and what took place on their Ruby Princes cruise Californian man Steve Lazarus is the first international coronavirus fatality linked to the ship

Californian man Steve Lazarus is the first international coronavirus fatality linked to the ship At least 35 cases in the US, UK, Canada and New Zealand have been traced back to the vessel

An electronic survey will be sent to more than 5,500 Australian and international passengers who sailed on the Ruby Princess between February 24 to March 8; and March 8 to March 19.

Assistant Commissioner Stuart Smith said the survey would ask passengers about their health, as well as what took place on the ship.

"The questionnaire will allow us to zero in on elements of the cruise we are interested in," he said.

"That goes hand in hand with the forensic examination of the telemetry box on the ship and those ship-to-shore communications that occurred."

A similar survey has been distributed to the ship's 1,000 crew members.

Superintendent Smith refused to confirm whether the coronavirus outbreak originated on the first cruise and spread to passengers on the second cruise.

"We're not going to speculate on either of those cruises," he said.

"We need to create a clear baseline in terms of the operation of the ship so that we can see … if there are any particular issues that we need to look at from the point of the second cruise."

There are now 20 deaths linked to the Ruby Princess and more than 900 cases of coronavirus.

Californian man Steven Lazarus is the first international fatality linked to the Ruby Princess's last voyage, and the ABC has traced at least 35 other international passengers who have also contracted coronavirus.

The ABC has confirmed six Ruby Princess passengers have tested positive for COVID-19 in Canada, one in Utah, two in California and at least one in the UK.

A cluster of 19 cases in the Hawkes Bay region of New Zealand is also linked to the ship's stopover in Napier during the cruise.

Steven Lazarus, left, and his son Michael, pictured at an ice hockey game. Steven died from coronavirus complications on April 9, 2020. ( Twitter: @mroblaz )

Eva Pallai and her boyfriend are among the Canadian passengers who tested positive.

"We were left in the dark," she said.

"Nobody told us there were cases on board. We were left roaming several airports and possibly contaminating others."

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Ms Pallai feared the true number of international cases could be higher, with legal action against operator Carnival Cruises now pending in US courts.

She told the ABC the ship's departure from Sydney on March 8 was delayed by more than seven hours due to "cleaning".

Ms Pallai said she asked crew members whether the cleaning was related to a previous coronavirus case onboard the ship but was reassured everything was ok.

"I straight out, point blank asked them 'Does this have to do with coronavirus? Are there any cases onboard?'," she said.

"They just lovingly, with a smile, said there were no issues.

"Nobody led me to believe there was a problem … so I got on, and my party got on."

Passenger Eva Pallai said staff were cleaning the Ruby Princess before it departed Sydney. ( Supplied: Eva Pallai )

Ms Pallai said the first indication something was wrong was when the coffee shop onboard the ship switched to disposable cups.

"The staff all over the lobby were washing handrails, they always do a great job of washing but I guess they were given orders to do even more."

She said she did not know she had been in contact with potentially infected passengers until she returned home to Canada via the US.

Ms Pallai developed symptoms two days later and tested positive to the disease on March 25, along with her partner, and her 70-year-old mother and stepfather.

She said she later learned from media reports that a female passenger on a previous voyage of the Ruby Princess was taken off the ship and had died of coronavirus.

Superintendent Stuart Smith said the investigation was one of the most complex ever to be undertaken by NSW Police, and involved interstate and overseas agencies.

He said the investigation could take longer than the six months originally slated, but there was nothing preventing the Ruby Princess from departing Australian waters.

"NSW Police investigators have finished their physical inquiries on the ship," he said

"There's nothing from an investigative point of view preventing the ship from disembarking."

Police Minister David Elliott said NSW Health would have the final say on when the ship could leave Port Kembla.