The special commission of inquiry, headed by Bret Walker SC, identified a series of "inexcusable", "inexplicable" and "unjustifiable" errors NSW authorities made before and after 2700 passengers were allowed to disembark into Sydney's Circular Quay.

Ms Berejiklian released the report immediately after receiving it on Friday afternoon, and will take Saturday and Sunday to read through its contents before commenting publicly.

When she does, NSW opposition leader Jodi McKay is calling for her to own up to the government's failings and formally apologise.

Commissioner Bret Walker SC reserved his harshest criticism for NSW Health, while absolving Australian Border Force officials of blame for the debacle.

The report noted that on March 10 the Communicable Diseases Network of Australia amended its guidelines such that everyone on board the ship with newly-defined suspect cases should be tested.

But those making decisions did not have the updated definition of a "suspect case" when undertaking a risk assessment on March 18.

"This was a serious and material error," the commission found.

The inquiry revealed the Ruby Princess outbreak infected 663 Australians on board and led to 28 deaths, including 20 domestically and eight in the United States.

The ship - which was low on medical supplies and swabs for COVID-19 tests due to shortages - left Sydney on March 8 for New Zealand and returned 11 days later.

Passengers disembarked before the results of 13 expedited tests showing at least three people had the virus.

The delay was inexcusable and the swabs should have been tested immediately, Mr Walker said.

Passengers were able to leave the ship as it had been deemed low risk by health officials as only 0.94 per cent had reported flu-like symptoms and had visited virus-hit nations.

The one per cent marker required to mandate NSW Health intervention had limited utility for assessing if COVID-19 was circulating onboard, the commission found.

The NSW government then erred by allowing disembarked passengers to immediately travel interstate and abroad, breaching a newly-minted public health order.

"Ultimately, every passenger and crew member of the Ruby Princess should have been tested for COVID-19 while in enforced quarantine," the inquiry said.

The ABF did not play any part in the mishap, Mr Walker said, given border officials' lack of medical or epidemiological expertise.

Prime Minister Scott Morrison on Saturday told Sydney's 2GB radio the report exonerated his government of any role in the blunder, after months of heavy criticism from Labor.

"It is as we said it was. We were being straight with people about what happened, and the inquiry has borne that out."

He also defended Ms Berejiklian's handling of the saga, saying the state has gone from strength to strength in managing the pandemic since.

"Officials will make mistakes in pandemics that none of us have had to manage before. And so, I think there's been some humble learnings out of New South Wales."

Separate NSW Police and coronial inquiries into the Ruby Princess are ongoing and not expected to report back for at least another month.

Australian Associated Press