The writing skills of Year 7 and 9 students have gone backward over the past decade, the latest national tests results reveal.

Preliminary results from this year's NAPLAN tests were released on Wednesday.

The alarming secondary school literacy and numeracy results show Year 7 and 9 achievements in writing were below the 2011 average.

While the performance of primary school students was above the 2008 average in many areas, the improvements were not seen in secondary school.

READ MORE NAPLAN results show Australian students falling behind in writing

Federal Education Minister Dan Tehan said state and territory governments should give greater autonomy to principals, and has urged parents to play a greater role through bodies like school councils.

"We've got to make sure that we're de-cluttering the curriculum so teachers can teach in the classroom," Mr Tehan told the ABC.

"Let's give more autonomy to parents and principals to be able to push on and implement these reforms."

The results for Year 5 numeracy, Years 3 and 5 reading, Years 3 and 5 spelling, and Year 3 grammar were above the 2008 average.

Australian Curriculum, Assessment and Reporting Authority chief executive David de Carvalho said schoolchildren had generally improved their writing skills when compared to last year's results.

"Overall, the results for 2019 show that since NAPLAN started in 2008, there have been gains in most test areas, particularly in the primary years," he said.

AAP

This year was the second time some of the tests were taken online, an option taken up by about half of schools.

But the system was plagued by technical issues, with some students losing connectivity and others unable to log in.

Affected students were able to resit the tests but the issue resulted in a disclaimer on the preliminary results warning they should be interpreted with care.

READ MORE Industry group backs NAPLAN methods amid criticism from experts

However, Australian Education Union acting president Meredith Peace said teachers and principals shouldn't trust the "seriously compromised" results.

"(The authority) is more concerned with saving its own skin and preserving a damaging test regime than ensuring the valid, consistent and reliable assessment of student achievement," she said.

Education academics are also warning the test results can't be fully relied upon, arguing the technical glitches have weakened NAPLAN's aim of providing comparable results.

Federal Labor education spokeswoman Tanya Plibersek said the government had failed to reverse declines in reading, writing and maths.

"Kids need to know the basics. It's the foundation of the rest of their education. We can't afford for the next generation to be held back," she told AAP.

All Australian students in Years 3, 5, 7 and 9 take part in the annual tests, which cover reading, writing, spelling, grammar and punctuation, as well as numeracy.

Teen disinterest prompts NAPLAN move call

Teenage disinterest is being blamed for the lacklustre performance by Year 9 students in national literacy and numeracy tests, prompting Victoria to call for a change in the year groups being put through the wringer.

Victorian Education Minister James Merlino wants to see the NAPLAN tests moved from Years 3, 5, 7 and 9 to Years 4, 6, 8 and 10.

READ MORE Review examines NAPLAN technical problems

He says Year 9 students struggle to make the connection between their test results and career potential.

"These results don't reflect what students are capable of and we must investigate options to ensure our Year 9 students are more engaged," Mr Merlino said in a statement on Wednesday.

READ MORE Thousands to re-sit NAPLAN tests

"This is about making the test more relevant, not adding unnecessary stress to NAPLAN."

He said moving the years tested up could give schools more timely information about achievement levels of students as they transition from primary school and would better enable students to use their results as they consider senior secondary choices.