The Victorian education minister James Merlino has called for an urgent review of Naplan online in the wake of reports that the release of the test results could be delayed.

Ahead of another emergency meeting between state education department bosses on Friday at which all options – including potentially not releasing some data – are on the table, Merlino accused the Australian Curriculum, Assessment and Reporting Authority (Acara) of botching the rollout of the test after months of reassurances.

“We were promised Naplan online testing would lead to quicker processing and schools, parents and students receiving their results sooner,” Merlino said on Thursday.

“It simply isn’t good enough that data from the online tests is currently not comparable with data from the paper tests. This only damages confidence in the online testing managed by Acara.

“We were promised Naplan online testing would lead to quicker processing and schools, parents and students receiving their results sooner. Clearly Naplan online has not been managed properly by Acara.

“However, in light of recent events, we need an urgent review by an independent expert into the delays and issues with comparing online and paper test data before we continue to progress Naplan online to a greater number of schools.”

His comments come after the Guardian revealed on Thursday that the Australian Capital Territory raised concerns about the comparability of online and written Naplan exams but was knocked back, months before it was revealed the release of the test results could be delayed.

On Wednesday it was revealed that the publication of preliminary Naplan results could be held up because of difficulties comparing test scores from students who sat the test online and those who did the written version.

Acara has denied that the release of the results has been delayed, and the federal education minister, Simon Birmingham, claimed opponents of the test were running a “scare campaign”.

But state education officials have voiced concerns about the comparability between the online and written results. On Thursday, Western Australia’s education minister, Sue Ellery, said that following a meeting between education officials on Wednesday the states were “still no clearer” on the status of the tests. She described it as “incredibly frustrating”.

Concerns about data comparability were serious enough that the ACT education minister, Yvette Berry, tried to have them included in a review of Naplan agreed to in June.

The review is assessing the My School website based on whether it provides “valid, reliable and contextualised” information, and whether the reporting of Naplan results balances “the community’s right to know with the need to avoid the misinterpretation or misuse of the information”.

It was described by Birmingham at the time as “narrow” in scope, despite a push from the ACT, Victoria and Queensland for a more wide-ranging look at the testing regime.

But Guardian Australia can reveal that the original terms of reference for the review put forward by Berry to the education council specifically asked for data comparability to be examined “although was not ultimately agreed”.

She said: “I’m obviously concerned about the emerging data comparability and reporting issues in the transition to online Naplan testing.”

While she did not say which states opposed it being included in the review, Birmingham said at the time that he had rejected “a review of Naplan that was … going to simply do what the unions have demanded, and lead to the dismantling of basic literacy, numeracy assessments across the country”.

The education council works by consensus, meaning all states and the commonwealth must agree for a decision to be made.

Berry said the goal of the review had been to assess the impact of Naplan reporting on the “high stakes culture of the test – in particular the stigmatising of lower scoring schools and the unfair stress and anxiety Naplan can place on students and their families”.

“All ACT public schools and the great majority of non-government schools transitioned to Naplan online this year and I’ll be looking to make sure the national response to this issue takes our local circumstances into account.”

It comes as department heads prepare to discuss the fallout from the delay at another meeting on Friday.

Correna Haythope, the head of the Australian Education Union, said the “misguided” trial of the online test had “shaken whatever confidence was left in the Naplan system” and blamed Birmingham.

“We understand the state and territory education directors-general are meeting in Canberra for another Naplan online crisis meeting. Clearly there is a problem - where does it lay? Is it in reading? Is it in writing? Is it in grammar and punctuation?”

“It is the responsibility of the Turnbull government [and] minister Birmingham to show some leadership and be completely transparent about finding the solutions to the issues being experienced with NAPLAN online.”