UPDATED 7.50am New Zealand teenagers are performing marginally worse in maths, science and reading than they were three years ago, but the country's global education ranks are up, according to a major study.

LISTEN ABOVE: Mark Robinson, Principal of Waiopehu College in Levin, spoke to Mike Hosking

The latest international Programme for International Student Assessment (PISA) study has given Kiwi 15-year-olds worse slightly scores in all three areas than three years ago - even when compared to a minor drop in the OECD average.

However New Zealand still remains above the OECD average in all three fields - with maths just over the line - and the Ministry of Education says the recent falls are too small to be considered statistically significant.

New Zealand ranked 12th in science (up from 18th in 2012), 10th in reading (up fro 13th) and 21st in maths (up from 23rd).

In 2000 New Zealand ranked fourth in maths - although the rankings are hard to read into due to changes in participating countries.

But in the 2012 results, New Zealand students' scores also slipped in every field - relative to other countries.

Principal of Waiopehu College in Levin Mark Robinson told Mike Hosking the report is too broad to work out, but we need to be pleased that we are still in the top half of the OECD countries.

"Twelfth in science. Tenth in reading. I think it's maths where we do need to do the work, so I think there is work to be done, but I think we should be pretty pleased."

The study gives 540,000 students in 72 countries a two-hour computer test in the three subjects, along with a background questionnaire.

Singapore ranked top of every field in the latest results.

The research also found New Zealand still had a large gap between poor and well- off students in results, and that Maori and Pasifika students were still lagging, with little change since 2012.

"I'm very proud of our students who achieved these excellent results, but it is balanced by my concern that we still have far too many in the lowest performing cohort and we see little shift in Maori and Pasifika from this group. So we have more to do," said Education Minister Hekia Parata.

The PISA report follows another global survey, TIMSS, which last week ranked New Zealand's Year 5 and Year 9 students the worst among English-speaking countries in maths.

Those results prompted calls from the opposition and unions for increased funding in schools.