Fewer than half of all packaged foods on New Zealand and Australian supermarket shelves could be classed as healthy, New Zealand researchers said Monday.

Surveys of the nutrient values of packaged food items available in 2012 quantified the proportion of products eligible to display health claims along with energy density, saturated fat, sugar and salt content, said University of Auckland researchers.

The study scored 23,596 packaged food and non-alcoholic drinks, 15,219 in Australia and 8,377 in New Zealand.

Across both countries only 45 percent of foods assessed were deemed healthy enough to carry health claims, but Australia, at 47 percent, did better than New Zealand at 41 percent.

"The few healthy choices available in key staple food categories is a concern," study lead professor Cliona Ni Mhurchu said in a statement.

"Dietary risk factors such as high salt and high saturated fat, low fruit and vegetable, and excess energy intakes, accounted for 11 percent of health loss in New Zealand in 2006. That is more than the burden of disease due to smoking (9 percent)," she said.

Improving diets and reducing salt intakes were priorities for global action following the United Nations high level meeting on non-communicable diseases in 2011.

"Processed foods contribute about three-quarters of dietary energy and nutrients consumed in high-income countries, so consumer food choices and the nutritional makeup of processed foods have enormous potential to influence dietary intakes," said Ni Mhurchu.

She recommended improving the nutritional quality of food and better nutrition labeling to inform consumers.