Assistant Minister for Health Fiona Nash launched a voluntary health star rating system last month which gives products a score of up to five stars based on their energy, fat, sugar and salt content.

More than three-quarters of respondents said the system should be made compulsory, in a poll of more than 1000 people commissioned by the Heart Foundation, Consumers Health Forum, Public Health Association and Obesity Policy Coalition.

Almost two-thirds of those polled agreed that "the food industry seems to have more say than the government over the regulation of food".

The results follow controversy over the introduction of health star ratings, with Senator Nash's former chief of staff Alastair Furnival at the centre of conflict-of-interest claims after revelations that he co-owned a lobbying firm representing junk food clients.

In other results, 85 per cent of those polled said unhealthy eating habits were a major problem for Australian children and half supported regulations on television advertising of junk food to children.

Half of people polled supported a tax on junk food and sugary drinks. This follows recent calls by some government ministers to extend the GST to fresh food, which has been widely opposed by health groups.

Health groups behind the poll said the results showed widespread support for action to tackle obesity amid concern over unhealthy diets.

Heart Foundation chief executive Mary Barry said Australia was facing a crisis, with about 60 per cent of Australian adults and a quarter of children now classified as overweight.

Of this group, about 25 per cent of adults and six per cent of children are obese.

Ms Barry said the government needed to immediately launch a national obesity prevention strategy which should include mandatory food labelling, restrictions on marketing of junk food to children and a tax on sugar-sweetened beverages.

"It's going to have to be a long-term commitment, like we've had to reduce the number of people smoking," she said.

Public Health Association of Australia president Heather Yeatman said significant increases in cancer, cardiovascular disease and diabetes would occur without urgent action to address dietary-related illness.

A spokeswoman for the federal health department said the government was encouraged to see food companies moving to implement health star ratings, making healthier choices easier for consumers. She said the voluntary system was due to be reviewed within two years.

The spokeswoman said the government funded a variety of other measures to address obesity, including guidelines and activities to encourage healthy eating and physical activity.