Ruby Princess passengers let off ship after border force officer confused flu and coronavirus test results

An Australian Border Force officer who inspected the Ruby Princess mistakenly believed passengers with flu-like symptoms had tested negative to Covid-19 when they had in fact tested negative to the flu.

That revelation, first reported by the ABC, is contained in documents to the New South Wales inquiry into the disastrous mid-March decision to allow 2,700 passengers to disembark the ship responsible for hundreds of Covid-19 cases and at least 22 deaths.

Labor has seized on the revelations the ABF officer had given informal clearance to disembark and then misunderstood testing results before a final decision. The shadow home affairs minister, Kristina Keneally, has called on the federal government to apologise after the head of the ABF previously blamed the NSW government for the incident.

Related: Ruby Princess inquiry: how distractions and mistakes led to a ‘catastrophic’ Covid-19 cluster

The commonwealth’s submission, seen by Guardian Australia, explains that after the Ruby Princess arrived in Sydney at 2.30am on 19 March, an ABF officer (Officer O) gave verbal authorisation to disembark between 6am and 7am – before test results had been obtained from passengers including at least 11 in isolation.

At 7.31am, a second ABF officer exchanged text messages with the NSW Health department, which advised the ship was “low risk” despite “elevated numbers of flu” and “all are OK to debark”.

Officer O was advised by a port agent that test results had come back negative. At 8.38am, the officer received a file prepared by the ship’s doctor, Ilse Von Watzdorf, entitled “lab form for coronavirus testing from a cruise ship” and headed “Ruby Princess/Specimens: Viral swabs”.

The form displayed a cross in the “tests required” field for Covid-19 PCR and a table with results, the final column of which recorded passengers’ “rapid flu test result” as “A+B Negative”.

The commonwealth’s submission said the ABF officer “quickly reviewed” this document and “misinterpreted” it, advising fellow officers that “all tests returned back NEGATIVE”.

Officer O then created a table indicating that all passengers had returned negative results for Covid-19 tests, and forwarded it to the agriculture department, responsible for biosecurity.

Ill passengers were allowed to disembark about 10am without being screened or entering any form of compulsory isolation.

The documents also contain an email exchange between 3.26pm and 4pm on 20 March – some 30 hours later – in which two other border force officers queried how passengers “all tested negative … and now some are positive” and appear to make the same error reading the form.

“There was confusion in the test results,” one said.

“Confusion? How so? It says negative …”

“Negative to the flu!!!!”

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The commonwealth submission concedes that although authorisation “appears not to have been formally granted before disembarkation, clearly passengers were permitted to disembark in advance of that occurring and no biosecurity officers sought to prevent passengers from disembarking”.

“In that sense, there was a practical granting of pratique (authorisation) to allow passengers to depart.”

Keneally said the prime minister, Scott Morrison, had guaranteed on 15 March that cruise ships would be “directly under the command of the ABF” but had since taken “no responsibility for failing to stop the one boat that mattered”.

“The Australian Border Force realised their grave mistakes on 20 March,” she said. “The Morrison government needs to come clean today – what did they know and when did they know it?”

Keneally called for an apology “to the hundreds of Australians who contracted Covid-19 because of the Ruby Princess – as well as the family members of the Australians who have tragically lost their lives”. She said federal officials should front the NSW inquiry.