Food flown into the UK will be stripped of its organic status unless it meets new stricter ethical standards, the Soil Association has warned.
The new measures will be put out to consultation next year
The association, which certifies 70% of the UK's £1.9bn organic food sector, says firms must show trade brings real benefit to developing world farmers.
It wants all air-freighted food to meet tough "ethical trade" standards.
But Trade and Development Minister Gareth Thomas said he feared the changes could harm African farmers.
The Soil Association says few overseas firms currently meet the planned new standards.
The rules will affect the 1% of the organic food market in the UK which is flown in from abroad, about 80% of which comes from low to lower-middle income countries.
The association's policy director Peter Melchett said some overseas producers would find it impossible to meet the standards.
"One of the things we assume this will do is eliminate the casual use of air freight," he added.
Anna Bradley, chair of the Soil Association's standards board, said: "It is neither sustainable nor responsible to encourage poorer farmers to be reliant on air freight but we recognise that building alternative markets that offer the same social and economic benefits as organic exports will take time."
The association has decided not to remove organic status from all air-freighted food saying that would hit producers in the developing world too hard.
We are worried about the livelihoods of the African farmers who don't meet these extra standards and we're worried about the costs of additional certification for the farmers that do meet the standards
Trade and Development Minister
It says it aims to balance the importance of the organic market for developing countries with rises in CO2 emissions.
Fairtrade-certified producers are given a minimum price covering the cost of sustainable production, and the Soil Association's ethical trade standards also aim to ensure a good deal for farmers.
The government said it welcomed the Soil Association's consultation on the issue, but it criticised the changes arguing they would impede organic exports from developing countries to the UK.
Trade and Development Minister Gareth Thomas said: "We are worried about the livelihoods of the African farmers who don't meet these extra standards and we're worried about the costs of additional certification for the farmers that do meet the standards."
His concerns were echoed by Patricia Francis, executive director of the Geneva-based International Trade Centre (ITC), which is a joint agency of the United Nations Conference on Trade and Development and the World Trade Organisation.
African farmers 'hurt'
She said: "African companies and cooperatives want to trade internationally. To get value-added organic foods on to retail shelves, they have an overwhelming amount of standards to meet.
"Meeting these standards costs money - laboratories, audits and more. Too many standards will hurt African farmers, which is just the opposite of what British consumers want.
Flying Matters, which represents airlines, said it welcomed the decision not to remove organic status from all air-freighted food from farmers in the developing world.
But chairman Brian Wilson said: "Unless teleportation becomes viable in the next few years there is no other alternative for them to get their fresh produce to market in good time."
The Soil Association's planned new measures will be put out to consultation next year, and it hopes they will be implemented from January 2009.