There is no evidence organic food is better for you than conventional food, minister David Miliband has said.
Mr Miliband says organic food is more of a "lifestyle" choice
The environment secretary said organic food was more of a "lifestyle choice that people can make".
There is no "conclusive evidence either way" concerning the health effects of pesticides, he told the Sunday Times.
The Soil Association, which regulates organic food, said studies show a difference between organic food and food produced using industrial methods.
It was critical of Mr Miliband's suggestion that food grown with the use of pesticides and other chemicals should not be regarded as inferior.
Mr Miliband: "It's only 4% of total farm produce, not 40%, and I would not want to say that 96% of our farm produce is inferior because it's not organic."
He said despite the rise in organic sales being "exciting" for shoppers, they should not think of conventionally-produced food as "second best".
Peter Kendall, president of the National Farmers' Union, added that he had seen "no evidence" to prove organic food is healthier.
"If there's a small but growing percentage of consumers who want a different product, then that's a great opportunity for members," he said.
"But I have a real problem with conventional methods being demeaned at every opportunity."
According to the Soil Association, organic food sales in the UK increased by 30% to £1.6bn in 2006.
Robin Maynard, the association's campaigns director, said the environment secretary's comments were "slightly disappointing".
"It has been shown over the years that there is a difference between food produced organically and that produced using industrial methods.
"It is not just a lifestyle choice in terms of the environment, organic is better for that.
"Mr Miliband's own government has recognised in the past that organic food can be better for that. In fact organic farmers get an extra payment due to this."
However, Mr Maynard admitted there was a lack of studies showing how organic food could be healthier.
He said this stemmed from the difficulties of pinpointing exactly how such food was healthier and because research needed to be carried out over "tens of years".
The association's website says organic food does not contain many of the artificial additives used in modern food production, and also have more natural vitamins and minerals.
It also argues organic food is better for wildlife because it does not use pesticides or dangerous sprays.
Pressure from shoppers has boosted the volume of organic UK produce in supermarkets, the association said last year.
Pete Glanville, secretary of the Shetland Organic Producers Group, said organic food is about producing local goods that are chemical free.
"You only have to look at the list of things that goes into creating lots of things to realise just how much we are not putting into our bodies by eating organic."
"We are not saying the other 96% which is farmed conventionally is rubbish. We personally are making a choice about what goes into our bodies."