There are calls for food manufacturers to declare on their packaging how much sugar has been added to their products.

New analysis has found 70 per cent of packaged foods sold on Australian supermarket shelves contain added sugar.

Soft drinks, cakes, pies, ice cream, pastries and processed meats are the worst offenders. On average they contain four times more added sugar than plain cereals or oats.

The findings of the analysis from the George Institute for Global Health at the University of NSW, published in the journal Nutrients, have led to calls for manufacturers to declare the amount of added sugar on the packaging.

"Good sugars are an integral part of a healthy diet, and we need to be able to separate sugars naturally present in dairy, fruits and vegetables from sugars added during manufacturing," said the Institute's Professor Bruce Neal.

''Added sugars are empty calories and a major contributing factor to the obesity epidemic and tooth decay," he said.

Researchers analysed more than 34,000 packaged foods - more than 18,000 discretionary foods and nearly 16,000 core foods like milk, bread and cheese.

Based on the Australian Dietary Guidelines, a significantly higher proportion of discretionary foods contained added sugar compared to core foods, 87 per cent versus 52 per cent.

The research will be submitted to the federal government's current review of the Health Star Rating (HSR) system.

Professor Neal says the HSR system gives consumers great advice most of the time, but only labelling total sugar content as opposed to added sugar can be misguiding.

This is particularly so for discretionary products such as muesli bars, jam, rice puddings, and chutney and other sauces and spreads, which contain a lot of added sugar but get a relatively high HSR in the current system.

Earlier this year, consumer group Choice released a report which found that if consumers could identify added sugars on food packs they could avoid 26 teaspoons of sugar each day.

With 50 per cent of Australian adults consuming more added sugar than they should, there is a clear need for improved labelling, Prof Neal said.

"We'd encourage food manufacturers to start labelling added sugars and government to provide the framework," he said.

"Australians would be much better off if they could quickly and easily see how much sugar has been added."