The latest "Trends in International Mathematics and Science" study, released on Tuesday, showed the ACT outperformed the other states and territories in year 4 maths and science and year 8 science, equal first with Victoria in year 8 maths.

It was also the jurisdiction with the highest percentage of students achieving the highest level in year 4 maths, year 4 science and year 8 science.

While this may indicate the ACT is performing strongly, when data is compared across the 20 years of TIMSS testing, results in the ACT have stagnated.

There was also a significant decline from 2011 in the year 8 science results.

ACT Education Minister Yvette Berry said this trend highlighted the specific areas ACT education needed to assess.

"We need to keep looking at how we can improve," Ms Berry said.

"That's why Labor took a clear plan for science, technology, engineering and maths to the election."

Australia as a whole has fared poorly, plummeting in the rankings with countries including Kazakhstan, Cyprus and Slovenia leapfrogging us in the past four years.

Australia dropped from 18th to 28th out of 49 countries in year 4 mathematics.

Australia fell from 12th to 17th in year 8 maths and from 12th to 17th in year 4 science while maintaining 25th place in year 8 science.

Education Minister Simon Birmingham said the disappointing results would form a key part of discussions with the states and territories about school funding for 2018 onwards.

"When I sit down with my state and territory counterparts in December these results highlight that we all need to focus on what evidence-backed initiatives will lift student outcomes and how is our funding best distributed to ensure it reaches those who need it most," Mr Birmingham said.

"A strong level of funding for our schools is obviously important but the focus of the Turnbull government is on how that money is being spent and what programs and initiatives should that money be supporting that will best help this and future generations of students."

Sue Thomson, director of educational monitoring and research at the Australian Council for Education Research, said the results were a "wake-up call" and that we were clearly "slipping backwards".

"Australia has remained in the middle of the pack in the past 20 years when other countries are improving," Dr Thomson said. "Not only that, but a substantial proportion of our students are below the Australian proficient standard, with roughly half of students in remote areas at or below that level.

"Clearly, we have a problem."

Dr Thomson said the results were particularly concerning because an increasing number of jobs required STEM skills.

While Australia's results have flatlined since 2007, high-performing countries such as Singapore and South Korea continue to pull ahead. Meanwhile countries such as Canada and England have improved their results and now outperform Australia.

Kazakhstan, which has a GDP per capita of $US10,546 ($14,100) against Australia's $US54,718 ($73,174), placed significantly below Australia in maths and science in 2011 but now outperforms us.

Ms Berry said the ACT could not rest on its laurels and while the TIMSS data provided an important insight into how ACT students were faring internationally it was important to remain focused on what could be achieved in ACT schools.

"We need to use it, alongside results from other indicators like the soon-to-be-released NAPLAN data, to really understand the areas where we are excelling and where we can improve," she said.

The NAPLAN National Report is due to be released on December 7.

The results from the 2015 Program for International Student Assessment, a triennial international survey that tests 15-year-olds in science, mathematics, reading, collaborative problem-solving and financial literacy, are due on December 6.

with Matthew Knott