The environment secretary has sparked controversy by suggesting that there is no evidence organic food is better than conventionally grown produce.

David Miliband said in an interview with the Sunday Times that organic food was more of a "lifestyle choice that people can make".

Organic producers' group the Soil Association claims that sales of its products increased by 30 per cent to £1.6bn last year.

But Miliband insisted that food grown with the use of pesticides and other chemicals should not be regarded as inferior.

"There isn't any conclusive evidence either way," he argued.

"It's only four per cent of total farm produce, not 40 per cent, and I would not want to say that 96 per cent of our farm produce is inferior because it's not organic."

He added that despite the rise in organic sales being "exciting" for shoppers, they should not think of conventionally-produced food as "second best".