And one in five Canberrans say they have avoided dining out because they feared the meal would be unsafe, a poll has found.

Labor and the Greens backed the ratings scheme before the 2012 election in response to concerns about the secrecy surrounding food safety breaches. Yet, two years on, the government is still to decide on the policy's details, such as whether it will be compulsory and when it will be introduced.

The Canberra Times reported in 2011 that, while inspectors had found dozens of eateries were too unclean to sell food, ACT laws prevented those businesses from being publicly identified.

The Newspoll survey of 1000 Canberrans, carried out in May this year, found 19 per cent of people had avoided buying from a food business at least once in the past year "because of a lack of confidence about food hygiene standards".

The fears were most prominent among young people – 27 per cent of those aged between 18 and 34 had avoided eateries – but receded with age.

The poll also showed strong public support for hygiene ratings: 81 per cent backed the scheme at least "somewhat", while only 4 per cent opposed it. More than one in eight Canberrans also said they would dine out more often if a scores-on-doors scheme was introduced.

Chief Minister Katy Gallagher said she commissioned the poll to help the food industry understand the benefits of transparency, not to test whether the policy was popular.

"The results are really strong: people say if they had scores on doors they would have more confidence about going to a venue and would eat out more," she said.

"It's clear that some people are not eating out because of concerns they have about food safety.

"I want businesses to understand this, because the industry has been criticising the scheme and saying it's just more red tape."

A KPMG analysis of the policy, published in 2012, suggested 60 to 80 per cent of food-borne illnesses were the result of meals bought at eateries.

It estimated that these food-poisoning cases cost the ACT economy between $61 million and $89 million a year, through pain and suffering, food recall and compensation costs, and flow-on effects due to productivity losses.

Industry groups, including the Australian Hotels Association, ClubsACT and the Australian Food and Grocery Council, had lobbied against a scores-on-doors scheme, saying it would be costly and there was no evidence that unhygienic practices were a widespread problem.

The Canberra Liberals had also reserved support for the policy, saying the government should first monitor whether its other initiatives – such as tougher training requirements for staff – were working effectively.

Last month, the Dickson restaurant at the centre of Canberra's worst-known mass poisoning, Copa Brazilian Churrasco, closed down.

The eatery served salmonella-contaminated mayonnaise on its opening weekend last year, poisoning more than 160 diners and hospitalising 15.