Retailers have been warned they need to do more to educate shoppers about organic food after research indicated nearly half of them do not believe food sold as organic actually is.

Of 1,000 shoppers surveyed by MarketTools, 49% said they did not believe that all products labelled organic were organic. Twelve per cent said they strongly agreed with this view and 37% simply that they agreed.

Scepticism was highest among organic shoppers themselves, with 50% of those who bought organic products doubting their authenticity, and 47% of those who didn't buy organics holding the same view. The survey highlighted the confusion among shoppers over certification and labelling, said Paul Simpson, senior research manager at MarketTools, adding that the onus was on retailers to tell consumers about what organic status actually meant.

"There needs to be a wider understanding of what organic labels mean," he said. "Consumers want reassurance that an organic mark isn't just a stamp on a label. Supermarkets need to do more."

With Organic Food Fortnight drawing to a close tomorrow, there was more bad news from the survey, with just 21% of respondents saying organic foods were worth paying more for.

Fifty-eight per cent said they would buy organic goods if they were cheaper. But only 15% said they regularly bought organic food, with 54% saying they sometimes bought it. Thirty-one per cent of respondents said they never bought organic.

Price was an obstacle to purchase, said Simpson, and retailers wanting to grow their share of this market would have to reassess their pricing strategies for organic - which could have serious ramifications for their suppliers.

"Over time this will lead to retailers applying pressure on manufacturers to supply cheaper organic products," he said.

MarketTools also found 55% of people ranked health as the main reason for buying organic. Twenty-three per cent said concern about the environment drove them to buy organic, with 22% saying it was because they believed organic food tasted better.