The Food Standards Agency of Australia and New Zealand recommended in a recent proposal that the B vitamin folic acid is added to all bread-making flour to help to reduce the number of babies born each year with birth defects.
Each year, 300 to 350 pregnancies in Australia and around 70 in New Zealand are affected by neural tube defects.
Women who are deficient in folic acid have been shown to have a higher risk of having a child with these defects.
But George Weston Foods, one of two Australian bakers that account for three quarters of all bread sales, says it has written to federal and state ministers urging them to reject the FSANZ proposal.
The company claims the proposal ignores both up-to-date information on women's current diets as well as adequate knowledge of the risks to others in the population from consuming more folic acid.
"We don't believe the authorities have done their research nor do they know what people eat," a spokesman for the firm told AP-Foodtechnology.com.
FSANZ spokeswoman Lydia Buchtmann says all research done by the regulator is based on science.
However George Weston argues that despite research showing that mandatory folic acid fortification in the US has reduced birth defects there, other countries have failed to implement similar initiatives because of evidence suggesting possible risks.
The company spokesman highlighted the case of the UK, which has stalled on a fortification programme due to potential risks for the elderly.
Folic acid intake can mask a deficiency of vitamin B12.
Buchtmann argues that Australia and New Zealand are advocating 'conservative levels' of fortification, which would not adversely impact any of the population.
However bakers are wary of being held responsible for adverse effects of folic acid fortification if negative effects are found in the future, according to George Weston.
"Legal opinion shows that if government gets it wrong, industry will be liable," said the firm's spokesman.
He denied that the baker was against the move because of the additional costs involved.
FSANZ estimates that it will add 1 per cent to the cost of a loaf of bread.
George Weston's consumer and regulatory affairs manager, Fiona Fleming, added that even if fortification can be shown to be safe, bread is not the most suitable vehicle for the vitamin.
Australian women are consuming less bread than previously, partly as a result of the recent low-carb trend.
A Newspoll survey commissioned by George Weston found that half of all women of child-bearing age consume no bread on any specific day.
In addition, daily consumption records compiled by a dietitian in Sydney show 21 per cent of women eat no bread at all.
"To obtain the recommended daily dose of folic acid women would have to eat about 11 slices of white bread each day.
But research shows that on average they only eat about 11 slices of bread in total a week," said Fleming.
She added that folic acid was already contained in many breads currently available and that mandating it in all breads would unnecessarily remove the freedom of choice that consumers currently have.
Others in the food industry have also called for voluntary fortification of a variety of foodstuffs to reduce the incidence of birth defects, as well as increased government education promoting such foods as well as supplements.
George Weston says it is prepared to back education programmes and is also talking to spina bifida charities about how to boost uptake of folic acid.
However Buchtmann points out that around half of all pregnancies are unplanned and for these pregnancies, women will not be able to up their folic acid intake early enough to offer sufficient protection to the foetus.