New research released by Cancer Council Australia and the National Heart Foundation of Australia shows Australian teenagers are spending increasing time in front of electronic devices such as computers, laptops, tablets, video games and TV.

The updated National Secondary Students' Diet and Activity Survey found 77 per cent of Australian teenagers spent more than two hours using electronic devices for entertainment on school days, compared with 71 per cent in 2009. The proportion of teenagers exceeding the recommended two hours of screen time per day on weekends also increased, from 83 to 89 per cent.

Chair of Cancer Council Australia's Public Health Committee, Craig Sinclair, said the increase in screen use threatened to undermine any modest benefit from a marginal improvement in physical activity levels, which remained critically low.

"As a parent, I know how fixated kids can be with their electronic devices, but we have to get our kids moving and complement increased physical activity with healthier eating," Mr Sinclair said.

Ms Mary Barry, Heart Foundation National CEO, said the research reiterated the need for a national physical activity strategy.

"Overweight and obesity among young people is a significant public health issue in Australia, with overweight adolescents being at increased risk of becoming overweight adults and experiencing chronic diseases such as heart disease," Ms Barry said.

Mr Sinclair said there had been a marginal improvement in exercise levels since 2010, but 82 per cent of teens were still not getting the recommended minimum of one hour's physical activity each day to help protect their long-term health.

Ms Barry said the modern day problem of increased use of electronic devices was emerging as a new frontier in the fight against obesity and inactivity with 58 per cent of students having at least three televisions at home and 40 per cent having one in their bedroom.

The survey also found four in 10 students have video games in their bedroom as well. The Heart Foundation and the Cancer Council believe parents, schools and policy makers have to work together to help ensure the use of electronic devices do not harm the long-term health of our young people.