The national assessment body says its data analysts have confirmed the two data sets can be compared, following reports some state and territory education department bosses due to meet in Canberra on Wednesday have concerns.

One in five students in years three, five, seven and nine who took the standardised tests did so online in the first year of a three-year rollout of online testing.

"As this is the first year of online assessment extra attention has been given to reviewing the data and ensuring it is comparable with previous years and between online and paper test modes," the Australian Curriculum, Assessment and Reporting Authority said on Wednesday.

Media reports suggest some education heads raised concerns at a meeting earlier this month about how the data would be released.

A number of options had been considered, including one combined public report, two separate reports or no report at all.

The authority also rejected suggestions there could be delays in releasing the results, confirming they're "on track" to be released soon.

The transition to online testing has received mixed responses.

Labor's Education Spokeswoman Tanya Plibersek wants to see the rollout happening faster, saying it was astounding that in 2018 students were still sitting pen and paper tests.

"NAPLAN online, if delivered well, could give students, parents and teachers more accurate and timely information," she said.

But the Australian Education Union boss Correna Haythorpe said it was a "disaster" and repeated the AEU's earlier calls for online tests to be scrapped.

"NAPLAN online is fundamentally flawed and must not be implemented," she said.

Education Minister Simon Birmingham said it was disappointing the union was taking advantage of extra consultations designed to ensure the first year of online results were ready for public release.

"Australians should see through the scare campaign being peddled by the union as little more than cheap opportunism from those who have always opposed parents receiving transparent and accountable information on student and school performance," Senator Birmingham said.

"The Turnbull government will always back parents and educators to get the information they need to help students reach their full potential in their education."

AAP